MG MM Straight Blade Insta-Act/Isolation Module

MG MM Straight Blade Insta-Act/Isolation Module
Fisher Engineering
July 2001
Lit No. 27179
MECHANIC'S GUIDE
®
S Y S T E M
SNO
WPL
OWS
SNOWPL
WPLO
Featuring the
Insta-Act® Hy
dr
aulic System
Hydr
draulic
and the
E-F
or
ce Isola
tion Module System
E-For
orce
Isolation
CAUTION
Read this manual before servicing the snowplow.
TABLE OF CONTENTS
PREFACE
Preface ............................................................................................................ 3
This guide has been prepared to help
the trained mechanic service FISHER®
snowplows. It also provides safety
information and recommendations.
We urge all mechanics to read this
manual carefully before attempting to
service the FISHER snowplow
equipment covered by this guide.
Safety Information .......................................................................................... 4
Product Specifications ................................................................................... 6
Required Tools ................................................................................................ 6
Hydraulic Hose Routing ................................................................................. 7
Hydraulic Unit Parts Diagram ........................................................................ 8
Service of your FISHER snowplow
equipment is best performed by your
local FISHER outlet. They know your
snowplow best and are interested in
your complete satisfaction.
Solenoid Cartridge Valve Identification and Location ................................ 9
Relief Valve Identification and Location .................................................... 10
Pilot-Operated Check Valve Identification and Location .......................... 11
Vehicle Harness and Vehicle Cable Location ............................................ 12
Operating the Snowplow ............................................................................. 13
Theory of Operation ..................................................................................... 15
Hydraulic and Electrical Schematics .......................................................... 17
Electrical Schematic .......................................................................... 18
Hydraulic Schematic ......................................................................... 19
Raise ................................................................................................... 20
Lower .................................................................................................. 22
Angle Right ......................................................................................... 24
Angle Left ........................................................................................... 26
Hold in Raise Position – Hydraulic ................................................... 28
Striking an Object While Plowing – Left Cylinder Retracts ........... 29
Striking An Object While Plowing – Right Cylinder Retracts ......... 30
High Beam Headlamps With Snowplow Connected to Vehicle .... 31
Low Beam Headlamps With Snowplow Connected to Vehicle ..... 32
Troubleshooting Guide ................................................................................. 33
Removable Spring Tool ............................................................................... 67
Lit. No. 27179
3
July 2001
SAFETY INFORMATION
WARNING
Indicates a potentially
hazardous situation that, if not
avoided, could result in death
or serious personal injury.
Warning Label
Please become familiar with and make owners
knowledgeable of the Warning and Instruction labels
on the back of the blade!
CAUTION
WARNING
LOWER BLADE WHEN VEHICLE IS PARKED.
REMOVE BLADE ASSEMBLY BEFORE PLACING VEHICLE
ON HOIST.
DO NOT EXCEED GVWR OR GAWR INCLUDING BLADE
AND BALLAST.
Indicates a situation that, if not
avoided, could result in minor
personal injury and/or damage
to product or property.
CAUTION
Warning Label
READ OWNER'S MANUAL BEFORE OPERATING OR
SERVICING SNOWPLOW.
TRANSPORT SPEED SHOULD NOT EXCEED 45 MPH.
REDUCE SPEED UNDER ADVERSE TRAVEL
CONDITIONS.
PLOWING SPEED SHOULD NOT EXCEED 10 MPH.
NOTE: Identifies tips, helpful hints
and maintenance information the
owner/operator should know.
REMOVE SLACK FROM CARRYING CHAIN BEFORE
TRAVELING.
SEE YOUR FISHER OUTLET FOR APPLICATION
RECOMMENDATIONS.
Instruction Label
21793
Instruction Label
U.S. Patents
4,280,062, 4,999,935,
5,353,530, 5,420,480
and other patents
pending
REMOVING PLOW
MOUNTING PLOW
BEFORE YOU BEGIN
A.
1. Drive vehicle forward fully
engaging pushplates into
attachment arms.
C.
1. Remove slack from carrying
chain and reattach.
2. Back vehicle away from plow.
Pushplate
Attachment
Arm
WARNING
Lower blade when vehicle is
parked. Temperature changes
could change hydraulic
pressure, causing the blade to
drop unexpectedly or
damaging hydraulic
components. Failure to do this
can result in serious personal
injury.
Jack Stand
B.
1. Twist connecting pin to release
tension.
2. Remove electrical covers on
vehicle.
3. Attach electrical connector to
corresponding connector on
vehicle.
4. Repeat steps B 1-3 on
passenger side of vehicle.
5. Connect hydraulic hoses to quick
disconnects. (BELT DRIVE
ONLY)
Jack Collar
Jack Leg
Connecting
Pin
Jack Lever
C
1. Release carrying chain and
reattach it leaving plenty of slack.
2. Push headgear upward toward
vehicle until connecting pins
snap in place.
3. Pull jack lever outward and raise
the jack stand.
Connecting Pin
Withdrawn
Jack
Stand
Headgear
Jack Lever
Jack Stand (Raised)
Lit. No. 27179
4
B.
1. Disconnect electrical connector
and reinsert in protective cover.
2. Insert release rod under jack
collar.
3. Push down on release rod as
you pull and twist connecting pin.
4. Repeat Steps B 1-3 on
passenger side.
5. Disconnect hydraulic hose
couplings and cover with dust
plugs.
A.
1. Place cab control in
"Lower/Float".
2. Push lift arm down.
3. Pull jack lever outward. Jack
stand will adjust to proper height.
8248
July 2001
SAFETY INFORMATION
BEFORE YOU BEGIN
WARNING
Do not exceed GVWR or GAWR
including blade and ballast.
The rating label is found on the
driver-side vehicle door
cornerpost.
WARNING
Remove blade assembly before
placing vehicle on hoist.
• Park the vehicle on a level surface,
place shift lever in PARK or
NEUTRAL and set parking brake.
• Leave the snowplow mounted on
the vehicle and lowered for most
service procedures, unless told
otherwise.
PERSONAL SAFETY
• Wear only snug-fitting clothing
while working on your vehicle or
snowplow.
• Do not wear jewelry or a necktie,
and secure long hair.
FIRE AND EXPLOSION
• Wear safety goggles to protect
your eyes from battery acid,
gasoline, dirt and dust.
WARNING
Gasoline is highly flammable
and gasoline vapor is
explosive. Never smoke while
working on vehicle. Keep all
open flames away from
gasoline tank and lines. Wipe
up any spilled gasoline
immediately.
• Avoid touching hot surfaces such
as the engine, radiator, hoses and
exhaust pipes.
• Always have a fire extinguisher
handy, rated BC for flammable
liquids and electrical fires.
VENTILATION
Be careful when using gasoline. Do
not use gasoline to clean parts. Store
only in approved containers away from
sources of heat or flame.
WARNING
Vehicle exhaust contains
deadly carbon monoxide (CO)
gas. Breathing this gas, even
in low concentrations, could
cause death. Never operate a
vehicle in an enclosed area
without venting exhaust to the
outside.
HYDRAULIC SAFETY
WARNING
Hydraulic oil under pressure
could cause skin injection
injury. If you are injured by
hydraulic oil, get medical
attention immediately.
If you work on the vehicle or snowplow
in a garage or other enclosed area, be
sure to vent exhaust gas directly to
the outside through a leakproof
exhaust hose.
• Always inspect hydraulic
components and hoses before
using. Replace any damaged or
worn parts immediately.
• If you suspect a hose leak, DO
NOT use your hand to locate it.
Use a piece of cardboard or wood.
• Always loosen plugs, fittings and
valves slowly to bleed off any
residual pressure.
BATTERY SAFETY
CAUTION
Batteries normally produce
explosive gases which can
cause personal injury.
Therefore, do not allow
flames, sparks or lit tobacco to
come near the battery. When
charging or working near a
battery, always cover your face
and protect your eyes, and
also provide ventilation.
Batteries contain sulfuric acid
which burns skin, eyes and
clothing.
Disconnect the battery before
removing or replacing any
electrical components.
• Be especially careful near moving
parts such as fan blades, pulleys
and belts.
Lit. No. 27179
5
July 2001
PRODUCT SPECIFICATIONS
Insta- Act® Hydraulic System
CAUTION
Available from your FISHER® outlet:
• Minute Mount® Electrical Tester
• Long Slender Needle Nose Pliers
• Isolation Module Tester
• Flat Screwdriver
• Removable Spring Tool
(for replacing trip springs)
• Sockets and Combination
Wrenches: 3/8" thru 7/8", 1-1/16",
1-1/8"
• Motor Relay Coil Resistance = 16
- 17 Ohms
• FISHER High Performance Fluid
to -25°F (-32°C)
• Unit Reservoir = 1-1/2 Quarts
Tools Required to service the
electrical and hydraulic
systems:
• Solenoid Coil Amp. Draw =
1.5 Amp.
Hydraulic Oil
Fluid Capacity—Hydraulic Oil
Electrical System –
approximate values:
• Solenoid Coil Resistance =
7 Ohms at room temperature
Do not mix different types of
hydraulic fluid. Some fluids
are not compatible and may
cause performance problems
and product damage.
®
REQUIRED TOOLS
• Motor Relay Amp. Draw =
0.7 Amp.
• Hydraulic Pressure Test Kit
(Available late 2001)
• Deep Socket: 7/8"
• 1/4" Socket or Nut Driver
• Motor Amp. Draw = 190 Amp. at
1750 psi
• 12 V Test Light
• Torque Wrench (in-lb)
• Switched Accessory Lead Draw =
0.75 Amp
• Allen Wrench Set
• System Total = 2-1/4 Quarts
• 3000 PSI Pressure Gauge
w/adapter fittings
Vehicle Control Harness Fuse Size
• Flashlight
Solenoid Valve Spool Travel =
• Park/Turn – 15 Amp. (ATC)
0.07" for three- and four-way valves
• Control – 7.5 Amp. (ATC)
(S2, S3) . Travel of two-way valve (S1)
spool is not detectable with voltage
applied to coil.
Mechanical
• Pick Set
• Hammer
• Digital Volt/Ohm Meter
• Pencil Magnet
Fastener Torque in IN–LB
• T-20 Torx
Pump Cap Screws ............................ 150 – 160
Motor Terminal Nuts..........................
50 – 60
Motor to Manifold Cap Screws ..........
30 – 40
Reservoir Screws ..............................
15 – 20
Valve Cartridges................................ 115 – 125
Coil Nuts ...........................................
48 – 60
Cartridge / Coil Cover Screws ...........
15 – 20
Check Valve ...................................... 115 – 125
Lit. No. 27179
6
July 2001
HYDRAULIC HOSE ROUTING
Lift Cylinder
Lift Hose
PS Angle Hose
Passenger-Side (right)
Angle Cylinder
DS Angle Hose
Driver-Side (left)
Angle Cylinder
Lit. No. 27179
7
July 2001
HYDRAULIC UNIT PARTS DIAGRAM
Motor
Threaded Area
Breather
Solenoid Coil
56662 Quill
Blocks
Stamped A11
and Higher
Cover
66509 Quill
Blocks
Stamped A10
and Lower
Coil Nut
Crossover Relief Valve
Solenoid Cartridge Valve
Valve Manifold Block
Bypass Check Valve
Crossover Relief Valve
Pump Relief Valve
Poppet Check Valve Kit
Pump
Suction Filter
O-Ring
Reservoir
Fill Plug
Drain Plug
Lit. No. 27179
8
July 2001
SOLENOID CARTRIDGE VALVE IDENTIFICATION AND LOCATION
Solenoid Cartridge Valve—S1
(SV08-2004)
Solenoid Cartridge Valve—S2
(SV08-31)
Solenoid Cartridge Valve—S3
(SV08-40)
Lit. No. 27179
9
July 2001
RELIEF VALVE IDENTIFICATION AND LOCATION
Right (Passenger Side)
Angle Cylinder Crossover Relief Valve
Quill Omitted for Clarity
Left (Driver Side)
Angle Cylinder Crossover Relief Valve
Pump
Relief Valve
See page 47 for detail.
Lit. No. 27179
10
July 2001
PILOT-OPERATED (POPPET TYPE) CHECK VALVE IDENTIFICATION AND LOCATION
Poppet Check Valve
See page 48 for detail.
Lit. No. 27179
11
July 2001
VEHICLE HARNESS AND VEHICLE CABLE LOCATION
Secondary (Large)
Terminals
Red Cable
Red Wire
Primary (Small)
Terminals
Motor
Relay
To Factory
Vehicle Harness
Long Plug-In
Harness
Black Cable
Turn Signal
Splice Wire
Brown/Red
Wire
Black/Orange
Wire
To Cab Control
Red Cable
PUR
To Vehicle
Headlamp
Red Wire
Vehicle
Cable Assembly
Firewall
Grommet
To a Switched Accessory Lead
Vehicle
Control Harness
Vehicle
Lighting Harness
15 Amp Fuse (Park/Turn)
7.5 Amp Fuse (Control)
Short Plug-In
Harness
Configuration Plug
For all others
To Front of Vehicle
4
To Factory
Vehicle
Harness
3
N
BR
R
PU
2
To Vehicle
Headlamp
1
For Storage
For '99–20_ GMC All New Sierra
and '99–20_ Chevy Silverado Only
Dust Plug
E-Force Isolation Module
Park/Turn Splice Wires
Lit. No. 27179
12
July 2001
OPERATING THE SNOWPLOW
Solenoid Control
WARNING
The driver shall keep
bystanders clear of the blade
when it is being raised,
lowered or angled. Do not
stand between the vehicle and
the blade, or within 8 feet of a
moving blade. A moving or
falling blade could cause
personal injury.
Mount the blade and attachments to
the vehicle. Make the three electrical
connections. Turn the vehicle ignition
switch to the ON or the ACCESSORY
position. Move control ON/OFF
switch to the ON position. The control
indicator light (red) should light
whenever the control ON/OFF switch
and the ignition (key) are both turned
ON.
CAUTION
To prevent accidental
movement of the blade,
always turn the ON/OFF switch
to OFF whenever the
snowplow is not in use. The
control indicator light will turn
off.
CAUTION
DO NOT hold control lever in
RAISE, ANGLE LEFT or ANGLE
RIGHT position after blade has
reached desired position. To
do so could result in the
hydraulic fluid overheating.
Turn the vehicle ignition switch on. Turn the control on. The control indicator light should be on.
Action
Description of Operation
ON/OFF
Slide the control power switch to ON to activate the hydraulic system. Turn the control OFF to lock the
blade in place. This prevents accidental movement of the blade.
Raise
Move the control lever up (forward) to raise the blade to the desired height.
Lower/Float
Move the control lever down (back) to lower the blade and activate the FLOAT mode.
Right
Move the control lever right to angle the blade to the right.
Left
Move the control lever left to angle the blade to the left.
Cancel
Float
Cancel the FLOAT mode by momentarily placing the control in the RAISE position, turning the control
off, or turning the vehicle ignition off. Angling left or right does not cancel float.
Emergency Stop
Lit. No. 27179
13
July 2001
OPERATING THE SNOWPLOW
Fish-Stik® Hand-Held Control
WARNING
2. Press the ON/OFF button on the
control. The control indicator light
glows red indicating the control is
on. The control indicator light
glows red whenever the control
ON/OFF switch and the vehicle
ignition switch are both ON.
CAUTION
The driver shall keep
bystanders clear of the blade
when it is being raised,
lowered or angled. Do not
stand between the vehicle and
the blade, or within 8 feet of a
moving blade. A moving or
falling blade could cause
personal injury.
To prevent accidental
movement of the blade,
always turn the ON/OFF switch
to OFF whenever the
snowplow is not in use. The
control indicator light will turn
off.
3. Press the LOWER button for 0.75
seconds to engage the FLOAT
mode. The control indicator
FLOAT light glows green. Cancel
the FLOAT mode by momentarily
pressing the RAISE button.
1. Turn the vehicle ignition switch to
the ON or the ACCESSORY
position. The control logo area
illuminates.
Function Time Outs
All control functions, except for
LOWER, automatically time out—
stop—after a period of time. This
helps prolong the battery charge. The
time-out period for the RAISE function
is 4.8 seconds, while the angle
function is 9.6 seconds.
The control automatically turns off
after being idle for 20 minutes.
Smooth Stop
The control automatically allows the
blade to coast to a stop. This results
in smoother operation, reduces the
shock to the hydraulic system and
increases hose and valve life.
ON/OFF
POWER
FLOAT
Emergency Stop
RAISE
R
I
G
H
T
L
E
F
T
LOWER
Button
Description of Operation
Raise
Press this button to raise the snowplow and to cancel the float mode.
NOTE: Snowplow automatically stops raising after 4.8 seconds. To resume raising the snowplow,
release the button and press again.
Press this button to lower the snowplow. NOTE: After reaching the desired height, release the button.
Holding the button down for more than 0.75 seconds activates the float mode, indicated by green
FLOAT lamp.
Press this button to angle blade to the right.
Press this button to angle blade to the left.
Cancel the float mode by momentarily pressing and releasing the RAISE button, turning control off, or
turning vehicle ignition off. Angling left or right momentarily cancels float.
Lower/
Float
Right
Left
Cancel
Float
Lit. No. 27179
14
July 2001
THEORY OF OPERATION
Snowplow Daytime Running
Lamps
Snowplow Headlamps
The Isolation Module acts as an
electrical hub, automatically directing
vehicle power to the appropriate
vehicle or snowplow lighting devices,
while also supplying battery power to
the snowplow control.
The vehicle high and low beams enter
and exit the Isolation Module through
positions 3 (left side lighting) and
position 4 (right side lighting). Park,
turn, and DRL signals also enter
through positions 3 and 4.
The output of the vehicle dimmer
switch is directed to the Isolation
Module via the long and short plug-in
harnesses. When the snowplow is not
attached to the vehicle, the signal
passes through the normally closed
relay contacts to the vehicle
headlamps. During this time, the
Isolation Module is inactive, placing no
current draw on the vehicle's electrical
system.
Turning on the vehicle parking lights
activates a series of relays,
automatically transferring the vehicle
high and low beams to the snowplow
while supplying battery power directly
to the snowplow parking lights. All
snowplow lighting exits the Isolation
Module through position 2.
Because Daytime Running Lamps
(DRLs) are controlled differently on
some vehicles, two Isolation Modules
have been developed.
The standard Isolation Module
transfers the DRL output from the
vehicle headlamps to the snowplow
lights when the vehicle ignition switch
is on and the snowplow is attached.
Turning on the vehicle ignition switch
energizes a snowplow control relay,
supplying vehicle battery power
directly to the control via the vehicle
control harness. The vehicle ignition
switch also supplies power to the
vehicle turn signals. Activating the
vehicle turn signals energizes turn
signal relays, which supply vehicle
battery power directly to the snowplow
turn signals.
The Isolation Module designed for the
1999-20_ GMC All New Sierra and
1999-20_ Chevy Silverado senses the
vehicle in the DRL mode. A series of
relays energize, placing the snowplow
headlamps in the DRL mode. This
Isolation Module does not turn off the
dedicated vehicle DRLs.
With the snowplow attached, the
Isolation Module is still inactive until
either of the two following conditions
are met: the vehicle parking lights are
turned on or the vehicle ignition switch
is turned on.
Lit. No. 27179
15
July 2001
THEORY OF OPERATION
Snowplow Hydraulics
The snowplow hydraulic system
performs four blade movements:
RAISE, LOWER, ANGLE RIGHT, AND
ANGLE LEFT.
All four movements require the vehicle
ignition (key) switch to be in the run or
accessory position and the cab
control to be turned on.
BLADE
MOVEMENT
Lit. No. 27179
Power to the three solenoid cartridge
valves is supplied by the vehicle
battery, via the Isolation Module and
cab control. The three solenoid
cartridge valves operate in various
combinations, electrically activated by
the cab control, to send hydraulic fluid
to the snowplow lift and angle
cylinders or back to the reservoir.
Three hydraulic movements require
energizing the electric motor, shifting
solenoid cartridge valve(s) or activating
check valves. The fourth function,
LOWER, does not energize the motor
but shifts a solenoid cartridge valve.
RAISE
LOWER
ANGLE
RIGHT
16
ANGLE
LEFT
July 2001
HYDRAULIC AND ELECTRICAL SCHEMATICS
This section contains hydraulic and
electrical schematics to help explain
how the hydraulic unit performs the
different functions. A schematic is an
abstract drawing showing the purpose
of each component in the system.
Each component is represented by a
graphical symbol. The hydraulic and
electrical legends describe each
symbol used in the schematics for
this guide.
HYDRAULIC LEGEND
LINE, WORKING (MAIN)
SPRING
LINE, PILOT (FOR CONTROL)
SOLENOID, SINGLE WINDING
WIRE SPLICE
PILOT OPERATED (P/O)
CHECK VALVE
LINES CROSSING
IN LINE CONNECTOR
FUSE
FLOW, DIRECTION OF
HYDRAULIC FLUID
VALVE, ADJUSTABLE
PRESSURE RELIEF
SOLENOID COIL
LINE, TO RESERVOIR
BELOW FLUID LEVEL
CIRCUIT GROUND
VALVE, FLOW CONTROL,
ADJUSTABLENON-COMPENSATED
HYDRAULIC PUMP
FIXED DISPLACEMENT
VALVE, TWO POSITION
TWO CONNECTION
(TWO WAY)
CYLINDER
• Bold lines and gray lines (ground)
represent the circuit being
activated only.
VALVE, TWO POSITION
THREE CONNECTION
(THREE-WAY)
ELECTRIC MOTOR
• Shaded components are either
activated or shifted from their
normal position.
VALVE, TWO POSITION
FOUR CONNECTION
(FOUR-WAY)
FILTER,STRAINER
DIFFUSER
NOTE: Left side = Driver side
Right side = Passenger
side
Lit. No. 27179
CROSSING WIRE
LINES JOINING
The first two schematics show an
overview of the complete hydraulic and
electrical systems. Other schematics
highlight the flow of hydraulic oil and
electrical current for each function the
hydraulic unit performs as well as the
flow of electrical current for the
snowplow and vehicle lights.
Wire Color Code
BLK
Black
BLK/ORN Black w/ Orange
BLK/RED Black w/ Red
BLK/WHT Black w/ White
BLU
Blue
ELECTRICAL LEGEND
Blue w/ Orange
Brown
Brown w/ Green
Brown w/ Red
Green
BATTERY
–
H
L
M
+
MOTOR
HEADLAMP
PARK/TURN LAMP
PRINTED CIRCUIT BOARD
COMPONENT ENCLOSURE
BLU/ORN
BRN
BRN/GRN
BRN/RED
GRN
MOTOR RELAY
GRY
LTBLU
LTGRN
ORN
PNK
Gray
Light Blue
Light Green
Orange
Pink
17
COMPONENT ENCLOSURE
PUR
RED
WHT
WHT/YEL
YEL
Abbreviations
Purple
DRL
Daytime Running Lamps
Red
MTR RLY Motor Relay
White
P/T SIG
Park / Turn Signal
White w/ Yellow
Yellow
July 2001
ELECTRICAL SCHEMATIC
LOCATED NEAR BATTERY
#6 RED
S3 SOLENOID
BLK/ORN
S2 SOLENOID
S1 SOLENOID
LT BLU
1
#6 BLK
WHT/YEL
PUMP MOTOR
- M + #6 BLK/RED
1
1
2
3
LT GRN
4
2
3
LT BLU
9
10
11
10
11
#6 BLK 2
#6 BLK/RED 1
2
1
WHT/YEL
RED
BRN
5
6
7
8
4
5
6
7
8
9
BLK/ORN
RIGHT SIDE PLOW LAMP
P
RED/YEL 1
LT GRN
2
BLK/ORN
3
BRN/RED
4
LT BLU 5
WHT/YEL
6
LOCATED AT FRONT OF VEHICLE
#6 BLK
T
LOCATED UNDER DASH
BLK/ORN
BRN/RED
RED/GRN
LT GRN
SOLENOID
CONTROL
BLK/ORN
12V BATTERY
PLOW ASSEMBLY
MTR RLY (Shown in
de-energized state)
#6 RED
LT BLU
LT GRN
2
3
4
5
6
WHT
GRN
BRN
BLK
BLU
RED
COIL CORD HARNESS
BLU
1
RED
2
YEL
3
ORN
4
GRN
5
WHT
6
BLK
WHT/YEL
T
BRN
RED/GRN
L
H
P
T
2
3
WHT
4
BLU/ORN
5
BLK
6
BLK/ORN
7
GRY
8
PUR
9
BRN
10
LT BLU 11
2
3
WHT/YEL
L
T
1
BLK/ORN
H
P
1
BRN
4
5
6
7
8
9
10
11
RED
BLK/ORN
TO SWITCHED ACCESSORY LEAD
5
6
6
7
7
A
RED
RED/YEL
B
C
D
RED/BLK
E
F
7.5-AMP CONTROL FUSE
RED/WHT
A
B
C
BLU/RED
BLU/WHT
H
J
K
WHT
BLK
A
A
B
C
BLU
BLK/ORN
WHT/YEL
BLK/WHT
PUR
BLK
BLK/ORN
GRY
GRY
BRN
LT BLU
PUR
BRN
LT BLU
BLU/ORN
LEFT HIGH BEAM OUT
LEFT LOW BEAM OUT
DRL SIGNAL IN
LEFT TURN IN
PARK LAMP IN
LEFT COMMON
FOR 1999-20_ GMC ALL NEW SIERRA
AND 1999-20_ CHEVY SILVERADO
TO VEHICLE HEADLAMPS,
PARK/TURN, DRL, AND
FACTORY VEHICLE HARNESSES
4
5
WHT/YEL
WHT
BLU/ORN
YEL
GRN
BRN
LEFT SIDE PLOW LAMP
3
4
CONFIGURATION PLUG
OR DUST COVER PLUG
BLK/WHT
LEFT LOW BEAM IN
LEFT HIGH BEAM IN
RED
2
3
15-AMP P/T FUSE
LOCATED AT FRONT OF VEHICLE
BLK/WHT
1
2
RED/YEL
#6 BLK
#6 RED
RED
P
HAND-HELD
CONTROL
1
LEFT COMMON
RED
ORN
PNK
PUR
BRN
BLU
LT BLU
RIGHT LOW BEAM IN
RIGHT HIGH BEAM IN
YEL
GRN
RIGHT HIGH BEAM OUT
RIGHT LOW BEAM OUT
RED
ORN
RIGHT TURN IN
PUR
RIGHT COMMON
RIGHT COMMON
BLU
LT BLU
LEFT LOW BEAM IN
LEFT HIGH BEAM IN
LEFT HIGH BEAM 2 IN **
LEFT HIGH BEAM OUT
A
B
C
D
E
F
G
H
J
K
A
B
C
D
E
F
G
H
J
K
LEFT LOW BEAM OUT
LEFT LOW BEAM 2 OUT**
3
LEFT TURN IN
PARK LAMP IN
TO VEHICLE HEADLAMPS,
PARK/TURN, AND FACTORY
VEHICLE HARNESSES
4
LEFT COMMON
LEFT COMMON
RIGHT LOW BEAM IN
RIGHT HIGH BEAM IN
RIGHT HIGH BEAM 2 IN**
RIGHT HIGH BEAM OUT
RIGHT LOW BEAM OUT
RIGHT LOW BEAM 2 OUT**
RIGHT TURN IN
RIGHT COMMON
RIGHT COMMON
YEL*
GRN
WHT
RED
ORN
WHT/YEL
PUR
BRN
BLU*
LT BLU
YEL*
GRN
WHT
RED
ORN
WHT/YEL
PUR
BLU*
LT BLU
G
B
C
D
E
F
G
ISOLATION MODULE
1
From Vehicle
Control Harness
2
From Vehicle
Lighting Harness
3
From Left Side
Vehicle Lights
4
From Right Side
Vehicle Lights
H
J
K
A
B
C
D
E
F
G
H
J
K
A
B
C
D
E
F
G
H
J
K
* HB-1 (9004) A= BLUE, J=YELLOW
** 99 DODGE RAM W/ SPORT PACKAGE
Lit. No. 27179
18
July 2001
HYDRAULIC SCHEMATIC
LIFT
CHECK
VALVE
VALVE MANIFOLD BLOCK
QUILL
S1
S2
PS CROSSOVER
RELIEF VALVE
RIGHT
LEFT
DS CROSSOVER
RELIEF VALVE
P/O
CHECK
VALVE
S3
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
ON
LOWER
ON
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
19
July 2001
RAISE – ELECTRICAL
Blade Movement: Raise
Control: Raise
System Response:
1) By moving control lever or pressing
the control button, the circuit
board within the cab control
switches power to the electrical
circuits.
2) Motor relay closes, current flows
through the motor relay, activating
the pump motor. +12V is applied
to the coil of solenoid cartridge
valve S3, shifting the spool.
3) Hydraulic oil from the pump flows
through solenoid cartridge valves
S3 & S2, through the internal
check valve in solenoid cartridge
valve S1 into the base end of the
lift cylinder causing it to extend.
1
S2 SOLENOID
BLK/ORN
S1 SOLENOID
PUMP MOTOR
M
-
+
LOCATED UNDER DASH
LOCATED AT FRONT OF VEHICLE
LT BLU
LT BLU
LT GRN
LT GRN
WHT/YEL
WHT/YEL
#6 BLK/RED
#6 BLK
BLK/ORN
#6 BLK/RED
#6 BLK
1
1
2
3
4
2
3
5
6
7
8
4
5
9
6
7
8
9
10
11
10
11
1
2
1
2
LT BLU
LT GRN
BRN
3
BLK
4
RED/YEL 1
LT GRN
2
BLK/ORN
3
BRN/RED
4
LT BLU 5
WHT/YEL
6
SOLENOID
CONTROL
GRN
2
SNOWPLOW ASSEMBLY
S3 SOLENOID
WHT
BLU
5
RED
6
COIL CORD HARNESS
BLU
1
RED
2
YEL
3
ORN
4
GRN
5
WHT
6
BLK
WHT/YEL
#6 RED
#6 BLK
HAND-HELD
CONTROL
1
2
3
4
5
6
7
1
2
3
4
PART OF ISOLATION MODULE
5
6
A
7
RED
RED/YEL
TO PLOW P/T GROUND
7.5-AMP CONTROL FUSE
RED/GRN
ON/OFF
L
E
F
T
LOWER
R
I
G
H
T
FLOAT
LOCATED NEAR BATTERY
POWER
FLOAT
RAISE
R
I
G
H
T
L
E
F
T
ON
U.S.PATENT NO.
4,999,935
#6 RED
BLK/ORN
TO PIN 2 OF VEHICLE
LIGHTING HARNESS
#6 RED
RED/WHT
B
C
D
E
F
G
1
From Vehicle
Control Harness
H
J
K
#6 BLK
BLK/ORN
BRN/RED
LOWER
RED/GRN
BLADE MOVEMENT
RAISE
Lit. No. 27179
MTR RLY
12V BATTERY
RAISE
OFF
TO SWITCHED ACCESSORY LEAD
20
July 2001
RAISE – HYDRAULIC
VALVE MANIFOLD BLOCK
LIFT
CHECK
VALVE
QUILL
S1
RIGHT
S2
PS CROSSOVER
RELIEF VALVE
P/O
CHECK
VALVE
LEFT
DS CROSSOVER
RELIEF VALVE
S3
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
ON
LOWER
ON
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
M
21
July 2001
LOWER – ELECTRICAL
Blade Movement: Lower / Float
Control: Lower
2) +12V is applied to the coil of
solenoid cartridge valve S1,
shifting the spool.
3) The weight of the plow forces the
lift cylinder to retract. The
retracting lift cylinder pushes the
hydraulic oil out of its base end,
through solenoid cartridge valves
S1 & S2 & S3, and back to the
reservoir.
System Response:
1) By moving control lever or pressing
the control button, the circuit
board within the cab control
switches power to the electrical
circuits.
1
2
SNOWPLOW ASSEMBLY
S3 SOLENOID
BLK/ORN
S2 SOLENOID
S1 SOLENOID
PUMP MOTOR
M
-
+
LOCATED AT FRONT OF VEHICLE
LT BLU
LT BLU
LT GRN
LT GRN
2
3
4
2
3
5
6
7
8
4
5
9
10
11
10
11
#6 BLK/RED
1
#6 BLK
2
1
2
WHT/YEL
#6 BLK
BLK/ORN
1
6
7
8
9
WHT/YEL
#6 BLK/RED
1
3
LOCATED UNDER DASH
RED/YEL
4
1
5
LT GRN
2
BLK/ORN
3
BRN/RED
4
LT BLU 5
WHT/YEL
6
LT BLU
LT GRN
6
WHT
SOLENOID
CONTROL
GRN
BRN
BLK
BLU
RED
COIL CORD HARNESS
BLU
1
RED
2
YEL
3
ORN
4
GRN
5
WHT/YEL
#6 RED
WHT
6
#6 BLK
NOTE: Angling left or right using
the Fish-Stik® handheld control
momentarily cancels Float while
the button is depressed. Float is
not cancelled by angling when
using the solenoid control.
BLK
HAND-HELD
CONTROL
1
2
3
4
5
6
7
1
3
4
PART OF ISOLATION MODULE
5
6
A
7
RED
RED/YEL
TO PLOW P/T GROUND
RED/GRN
LOWER
R
I
G
H
T
FLOAT
POWER
FLOAT
RAISE
R
I
G
H
T
L
E
F
T
ON
U.S.PATENT NO.
4,999,935
#6 RED
MTR RLY
BLK/ORN
TO PIN 2 OF VEHICLE
LIGHTING HARNESS
#6 RED
12V BATTERY
L
E
F
T
7.5-AMP CONTROL FUSE
LOCATED NEAR BATTERY
ON/OFF
RAISE
OFF
TO SWITCHED ACCESSORY LEAD
2
RED/WHT
B
C
D
E
F
G
1
From Vehicle
Control Harness
H
J
K
#6 BLK
BLK/ORN
BRN/RED
LOWER
RED/GRN
BLADE MOVEMENT
LOWER
Lit. No. 27179
22
July 2001
LOWER – HYDRAULIC
LIFT
VALVE MANIFOLD BLOCK
QUILL
CHECK
VALVE
S1
S2
PS CROSSOVER
RELIEF VALVE
RIGHT
LEFT
DS CROSSOVER
RELIEF VALVE
P/O
CHECK
VALVE
S3
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
ON
LOWER
ON
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
M
23
July 2001
ANGLE RIGHT – ELECTRICAL
Blade Movement: Angle Right
Control: Right
System Response:
1) By moving control lever or pressing
the control button, the circuit
board within the cab control
switches power to the electrical
circuits.
2) Motor relay closes, current flows
through the motor relay, activating
the pump motor. +12V is applied
to the coil of solenoid cartridge
valve S2, shifting its spool.
3) Hydraulic oil from the pump flows
through solenoid cartridge valve
S3, P/O check valve and into the
base end of the left cylinder
causing it to extend.
1
2
SNOWPLOW ASSEMBLY
S3 SOLENOID
BLK/ORN
S2 SOLENOID
S1 SOLENOID
PUMP MOTOR
M
-
+
LOCATED UNDER DASH
LOCATED AT FRONT OF VEHICLE
LT BLU
LT BLU
LT GRN
LT GRN
2
3
4
2
3
5
6
7
8
4
5
9
10
11
10
11
#6 BLK/RED
1
#6 BLK
2
1
2
WHT/YEL
#6 BLK
BLK/ORN
1
6
7
8
9
WHT/YEL
#6 BLK/RED
1
RED/YEL
4
5
1
LT GRN
2
BLK/ORN
3
BRN/RED
4
LT BLU 5
WHT/YEL
6
LT BLU
LT GRN
3
6
WHT
SOLENOID
CONTROL
GRN
BRN
BLK
BLU
RED
COIL CORD HARNESS
BLU
1
RED
2
YEL
3
ORN
4
GRN
5
WHT
6
BLK
WHT/YEL
#6 RED
#6 BLK
4) The retracting right cylinder
pushes the hydraulic oil out of its
base end, through solenoid
cartridge valves S2 & S3 back to
the reservoir.
HAND-HELD
CONTROL
1
2
3
4
5
6
7
1
2
3
4
PART OF ISOLATION MODULE
5
6
A
7
RED
RED/YEL
TO PLOW P/T GROUND
7.5-AMP CONTROL FUSE
RED/GRN
L
E
F
T
LOWER
R
I
G
H
T
FLOAT
POWER
FLOAT
RAISE
R
I
G
H
T
L
E
F
T
ON
U.S.PATENT NO.
4,999,935
#6 RED
MTR RLY
BLK/ORN
TO PIN 2 OF VEHICLE
LIGHTING HARNESS
#6 RED
12V BATTERY
LOCATED NEAR BATTERY
ON/OFF
RAISE
OFF
TO SWITCHED ACCESSORY LEAD
RED/WHT
B
C
D
E
F
G
1
From Vehicle
Control Harness
H
J
K
#6 BLK
BLK/ORN
BRN/RED
LOWER
RED/GRN
BLADE MOVEMENT
ANGLE RIGHT
Lit. No. 27179
24
July 2001
ANGLE RIGHT – HYDRAULIC
LIFT
VALVE MANIFOLD BLOCK
QUILL
CHECK
VALVE
S1
S2
PS CROSSOVER
RELIEF VALVE
RIGHT
P/O
CHECK
VALVE
LEFT
DS CROSSOVER
RELIEF VALVE
S3
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
ON
LOWER
ON
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
M
25
July 2001
ANGLE LEFT – ELECTRICAL
Blade Movement: Angle Left
Control: Left
System Response:
1) By moving control lever or pressing
the control button, the circuit
board within the cab control
switches power to the electrical
circuits.
2) Motor relay closes, current flows
through the motor relay, activating
the pump motor. +12V is applied
to the coil of solenoid cartridge
valves S2 & S3, shifting both
spools.
3) Hydraulic oil from the pump flows
through solenoid cartridge valves
S3 & S2 and into the base end of
the right cylinder causing it to
extend.
WHT
1
S3 SOLENOID
BLK/ORN
S2 SOLENOID
S1 SOLENOID
PUMP MOTOR
-
M
+
LOCATED UNDER DASH
LOCATED AT FRONT OF VEHICLE
LT BLU
LT BLU
LT GRN
LT GRN
2
3
4
2
3
5
6
7
8
4
5
9
10
11
10
11
#6 BLK/RED
1
#6 BLK 2
1
2
WHT/YEL
#6 BLK
BLK/ORN
1
6
7
8
9
WHT/YEL
#6 BLK/RED
1
RED/YEL
LT GRN
BLK
BLU
5
LT GRN
2
BLK/ORN
3
BRN/RED
4
LT BLU 5
WHT/YEL
6
LT BLU
BRN
3
4
1
RED
6
HAND-HELD
CONTROL
COIL CORD HARNESS
BLU
1
RED
2
WHT/YEL
YEL
3
ORN
4
GRN
5
#6 RED
#6 BLK
5) The retracting left cylinder pushes
the hydraulic oil out of its base
end, through the open P/O check
valve and solenoid cartridge valve
S3 and back to the reservoir.
GRN
2
SNOWPLOW ASSEMBLY
SOLENOID
CONTROL
4) Pressure within the hydraulic
circuit causes the P/O check valve
to open.
WHT
6
BLK
1
2
3
4
5
6
7
1
3
4
PART OF ISOLATION MODULE
5
6
A
7
RED
RED/YEL
TO PLOW P/T GROUND
7.5-AMP CONTROL FUSE
RED/GRN
ON/OFF
L
E
F
T
LOWER
R
I
G
H
T
FLOAT
POWER
FLOAT
RAISE
R
I
G
H
T
L
E
F
T
ON
U.S.PATENT NO.
4,999,935
LOCATED NEAR BATTERY
#6 RED
TO PIN 2 OF VEHICLE
LIGHTING HARNESS
BLK/ORN
#6 RED
RED/WHT
B
C
D
E
F
G
1
From Vehicle
Control Harness
H
J
K
#6 BLK
BLK/ORN
BRN/RED
LOWER
RED/GRN
BLADE MOVEMENT
ANGLE LEFT
Lit. No. 27179
MTR RLY
12V BATTERY
RAISE
OFF
TO SWITCHED ACCESSORY LEAD
2
26
July 2001
ANGLE LEFT – HYDRAULIC
LIFT
CHECK
VALVE
VALVE MANIFOLD BLOCK
QUILL
S1
RIGHT
S2
PS CROSSOVER
RELIEF VALVE
P/O
CHECK
VALVE
LEFT
DS CROSSOVER
RELIEF VALVE
S3
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
ON
LOWER
ON
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
M
27
July 2001
HOLD IN RAISE POSITION – HYDRAULIC
Blade Movement: Striking an Object While Plowing
Control: None
LIFT
System Response:
QUILL
CHECK
VALVE
1) Hydraulic oil is trapped in the base
end of the lift cylinder by the
internal check valve in solenoid
cartridge valve S1.
VALVE MANIFOLD BLOCK
S1
2) When the snowplow contacts an
object, the force of the impact
increases the hydraulic pressure
in the base end of the cylinder.
When the pressure exceeds the
relief valve pressure setting, the
relief valve opens allowing oil to
flow to the base of the opposite
cylinder.
S2
PS CROSSOVER
RELIEF VALVE
RIGHT
LEFT
DS CROSSOVER
RELIEF VALVE
P/O
CHECK
VALVE
S3
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
LOWER
ON
ON
28
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
M
July 2001
STRIKING AN OBJECT WHILE PLOWING – LEFT HYDRAULIC CYLINDER RETRACTS
Blade Movement: Striking an Object While Plowing
Control: None
System Response:
LIFT
CHECK
VALVE
1) Hydraulic oil is trapped in the base
end of the cylinders by the relief
valves, the P/O check valve and
solenoid cartridge valve S2.
VALVE MANIFOLD BLOCK
QUILL
S1
FORCE APPLIED
WHEN BACK DRAGGING
2) When the snowplow contacts an
object, the force of the impact
increases the hydraulic pressure
in the base end of the cylinder.
When the pressure exceeds the
relief valve pressure setting, the
relief valve opens allowing oil to
flow to the base of the opposite
cylinder.
S2
PS CROSSOVER
RELIEF VALVE
RIGHT
P/O
CHECK
VALVE
LEFT
DS CROSSOVER
RELIEF VALVE
S3
FORCE APPLIED
WHEN PUSHING
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
ON
LOWER
ON
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
29
M
July 2001
STRIKING AN OBJECT WHILE PLOWING – RIGHT HYDRAULIC CYLINDER RETRACTS
Blade Movement: Striking an Object While Plowing
Control: None
VALVE MANIFOLD BLOCK
LIFT
System Response:
1) Hydraulic oil is trapped in the base
end of the cylinders by the relief
valves, the P/O check valve and
solenoid cartridge valve S2.
QUILL
CHECK
VALVE
2) When the snowplow contacts an
object, the force of the impact
increases the hydraulic pressure
in the base end of the cylinder.
When the pressure exceeds the
relief valve pressure setting, the
relief valve opens allowing oil to
flow to the base of the opposite
cylinder.
S1
FORCE APPLIED
WHEN PUSHING
S2
PS CROSSOVER
RELIEF VALVE
RIGHT
P/O
CHECK
VALVE
LEFT
DS CROSSOVER
RELIEF VALVE
S3
FORCE APPLIED
WHEN BACK DRAGGING
PUMP
RELIEF
VALVE
BLADE
MOVEMENT
MOTOR
SV08-2004
SV08-31
SV08-40
Lit. No. 27179
M
S1
S2
S3
RAISE
ON
ON
LOWER
ON
ANGLE
RIGHT
ANGLE
LEFT
ON
ON
ON
ON
ON
30
M
July 2001
HIGH BEAM HEADLAMPS WITH PLOW CONNECTED TO VEHICLE
LOCATED NEAR BATTERY
#6 RED
S3 SOLENOID
LT BLU
BLK/ORN
LT GRN
LT BLU
LT GRN
BLK/ORN
RIGHT SIDE PLOW LAMP
T
P
WHT/YEL
RED
BRN
#6 BLK
#6 BLK/RED
BRN
L
H
T
1
2
3
4
2
3
5
6
7
8
4
5
LT BLU
LT GRN
9
6
7
8
9
10
11
10
11
2
1
#6 BLK
2 #6 RED
1
4
5
6
GRN
BRN
BLK
BLU
RED
COIL CORD HARNESS
BLU
1
RED
2
YEL
3
ORN
4
GRN
5
WHT
6
BLK
WHT/YEL
BRN
HAND-HELD
CONTROL
1
1
2
2
3
3
4
4
TO SWITCHED ACCESSORY LEAD
5
5
6
6
7
7
RED
RED/YEL
RED/YEL
15-AMP P/T FUSE
RED/GRN
1
1
2
3
4
2
3
5
BLK
6
BLK/ORN
7
GRY
8
PUR
9
BRN
10
LT BLU 11
4
5
6
7
8
9
10
11
CONFIGURATION PLUG
OR DUST COVER PLUG
BLK/WHT
BLK/ORN
A
B
C
A
B
C
WHT/YEL
WHT
BLU/ORN
GRY
LEFT LOW BEAM IN
LEFT HIGH BEAM IN
YEL
GRN
LEFT HIGH BEAM OUT
LEFT LOW BEAM OUT
DRL SIGNAL IN
LEFT TURN IN
PARK LAMP IN
LEFT COMMON
RED
FOR 1999-20_ GMC ALL NEW SIERRA
AND 1999-20_ CHEVY SILVERADO
TO VEHICLE HEADLAMPS,
PARK/TURN, DRL, AND
FACTORY VEHICLE HARNESSES
LEFT COMMON
RIGHT LOW BEAM IN
RIGHT HIGH BEAM IN
RIGHT HIGH BEAM OUT
RIGHT LOW BEAM OUT
RIGHT TURN IN
RIGHT COMMON
RIGHT COMMON
RED
ORN
PNK
PUR
BRN
BLU
LT BLU
YEL
GRN
RED
ORN
PUR
BLU
LT BLU
LEFT LOW BEAM IN
LEFT HIGH BEAM IN
LEFT HIGH BEAM 2 IN **
LEFT HIGH BEAM OUT
A
B
C
D
E
F
G
H
J
K
A
B
C
D
E
F
G
H
J
K
LEFT LOW BEAM OUT
LEFT LOW BEAM 2 OUT**
3
LEFT TURN IN
PARK LAMP IN
TO VEHICLE HEADLAMPS,
PARK/TURN, ANDFACTORY
VEHICLE HARNESSES
4
LEFT COMMON
LEFT COMMON
RIGHT LOW BEAM IN
RIGHT HIGH BEAM IN
RIGHT HIGH BEAM 2 IN**
RIGHT HIGH BEAM OUT
RIGHT LOW BEAM OUT
RIGHT LOW BEAM 2 OUT**
RIGHT TURN IN
RIGHT COMMON
RIGHT COMMON
E
F
G
H
J
K
WHT
BLK
A
BLU/ORN
BRN
B
C
D
BLU/RED
BLU/WHT
GRY
BRN
LT BLU
PUR
BRN
LT BLU
LEFT SIDE PLOW LAMP
RED/BLK
RED/WHT
BLU
BLK/ORN
WHT/YEL
BLK/WHT
PUR
BLK
BLK/ORN
RED
ISOLATION MODULE
A
7.5-AMP CONTROL FUSE
WHT
BLU/ORN
L
P
1
LOCATED AT FRONT OF VEHICLE
BLK/ORN
WHT/YEL
H
T
1
LT GRN
2
BLK/ORN
3
BRN/RED
4
LT BLU 5
WHT/YEL
6
3
SOLENOID
CONTROL
WHT
RED
BLK/WHT
P
RED/YEL
LOCATED AT FRONT OF VEHICLE
#6 BLK
P
LOCATED UNDER DASH
BLK/ORN
BRN/RED
WHT/YEL
PUMP MOTOR
- M + #6 BLK/RED
T
1
2
#6 BLK
RED/GRN
S2 SOLENOID
S1 SOLENOID
BLK/ORN
12V BATTERY
PLOW ASSEMBLY
MTR RLY (Shown in
de-energized state)
#6 RED
YEL*
GRN
WHT
RED
ORN
WHT/YEL
PUR
BRN
BLU*
LT BLU
YEL*
GRN
WHT
RED
ORN
WHT/YEL
PUR
BLU*
LT BLU
B
C
D
E
F
G
1
From
Vehicle
Control
Harness
2
From
Vehicle
Lighting
Harness
H
J
K
A
B
C
D
E
F
G
3
From
Left Side
Vehicle
Lights
4
From
Right Side
Vehicle
Lights
H
J
K
A
B
C
D
E
F
G
H
J
K
* HB-1 (9004) A= BLUE, J=YELLOW
** 99 DODGE RAM W/ SPORT PACKAGE
Lit. No. 27179
31
July 2001
LOW BEAM HEADLAMPS WITH PLOW CONNECTED TO VEHICLE
LOCATED NEAR BATTERY
#6 RED
S3 SOLENOID
LT BLU
BLK/ORN
#6 BLK
LT GRN
BLK/ORN
LT BLU
LT GRN
BRN
#6 BLK
2
#6 BLK/RED 1
2
1
LT BLU
LT GRN
3
4
5
6
SOLENOID
CONTROL
WHT
GRN
BRN
BLK
BLU
RED
COIL CORD HARNESS
BLU
1
RED
2
YEL
3
ORN
4
GRN
5
WHT
6
BLK
WHT/YEL
BRN
BRN
1
2
2
3
3
4
4
TO SWITCHED ACCESSORY LEAD
5
5
6
6
7
7
RED
#6 RED
RED/YEL
15-AMP P/T FUSE
RED/GRN
LOCATED AT FRONT OF VEHICLE
1
1
2
3
WHT
4
BLU/ORN
5
BLK
6
BLK/ORN
7
GRY
8
PUR
9
BRN
10
LT BLU 11
2
3
4
5
6
7
8
9
10
11
CONFIGURATION PLUG
OR DUST COVER PLUG
BLK/WHT
BLK/ORN
A
B
C
A
B
C
GRY
GRY
BRN
LT BLU
PUR
BRN
LT BLU
BLU/ORN
LEFT LOW BEAM IN
LEFT HIGH BEAM IN
BRN
LEFT HIGH BEAM OUT
LEFT LOW BEAM OUT
DRL SIGNAL IN
LEFT TURN IN
PARK LAMP IN
LEFT COMMON
RED
FOR 1999-20_ GMC ALL NEW SIERRA
AND 1999-20_ CHEVY SILVERADO
TO VEHICLE HEADLAMPS,
PARK/TURN, DRL, AND
FACTORY VEHICLE HARNESSES
BLU
BLU/RED
BLU/WHT
BLK/ORN
WHT/YEL
BLK/WHT
PUR
BLK
BLK/ORN
LEFT SIDE PLOW LAMP
RED/BLK
RED/WHT
WHT
BLK
WHT/YEL
WHT
BLU/ORN
RED
LEFT COMMON
YEL
GRN
RED
ORN
PNK
PUR
BRN
BLU
LT BLU
RIGHT LOW BEAM IN
RIGHT HIGH BEAM IN
YEL
GRN
RIGHT HIGH BEAM OUT
RIGHT LOW BEAM OUT
RED
ORN
RIGHT TURN IN
RIGHT COMMON
RIGHT COMMON
PUR
BLU
LT BLU
LEFT LOW BEAM IN
LEFT HIGH BEAM IN
LEFT HIGH BEAM 2 IN **
LEFT HIGH BEAM OUT
A
B
C
D
E
F
G
H
J
K
A
B
C
D
E
F
G
H
J
K
LEFT LOW BEAM OUT
LEFT LOW BEAM 2 OUT**
3
LEFT TURN IN
PARK LAMP IN
TO VEHICLE HEADLAMPS,
PARK/TURN, ANDFACTORY
VEHICLE HARNESSES
4
ISOLATION MODULE
A
7.5-AMP CONTROL FUSE
WHT/YEL
H
HAND-HELD
CONTROL
1
RED/YEL
#6 BLK
RED
L
T
5
6
7
8
4
5
RED
L
P
2
3
10
11
H
T
2
3
4
10
11
WHT/YEL
BLK/WHT
BLK/ORN
P
1
9
BLK/ORN
T
1
6
7
8
9
RIGHT SIDE PLOW LAMP
P
RED/YEL 1
LT GRN
2
BLK/ORN
3
BRN/RED
4
LT BLU 5
WHT/YEL
6
LOCATED AT FRONT OF VEHICLE
#6 BLK
P
2
LOCATED UNDER DASH
BRN/RED
WHT/YEL
PUMP MOTOR
- M + #6 BLK/RED
T
1
RED/GRN
S2 SOLENOID
S1 SOLENOID
BLK/ORN
12V BATTERY
PLOW ASSEMBLY
MTR RLY (Shown in
de-energized state)
#6 RED
LEFT COMMON
LEFT COMMON
RIGHT LOW BEAM IN
RIGHT HIGH BEAM IN
RIGHT HIGH BEAM 2 IN**
RIGHT HIGH BEAM OUT
RIGHT LOW BEAM OUT
RIGHT LOW BEAM 2 OUT**
RIGHT TURN IN
RIGHT COMMON
RIGHT COMMON
YEL*
GRN
WHT
RED
ORN
WHT/YEL
PUR
BRN
BLU*
LT BLU
YEL*
GRN
WHT
RED
ORN
WHT/YEL
PUR
BLU*
LT BLU
B
C
D
E
F
G
1
From
Vehicle
Control
Harness
2
From
Vehicle
Lighting
Harness
H
J
K
A
B
C
D
E
F
G
H
J
K
A
B
C
D
E
F
G
3
From
Left Side
Vehicle
Lights
4
From
Right Side
Vehicle
Lights
H
J
K
A
B
C
D
E
F
G
H
J
K
* HB-1 (9004) A= BLUE, J=YELLOW
** 99 DODGE RAM W/ SPORT PACKAGE
Lit. No. 27179
32
July 2001
TROUBLESHOOTING GUIDE
Troubleshooting Guide
Contents
General Diagnostic Table .......... 34
Packing Nut Adjustment ............. 37
Motor Test .................................... 38
Motor and Motor Relay Test
Diagram ....................................... 39
Motor Relay Test ......................... 40
Vehicle Control Harness Test ..... 41
Control Test ................................. 43
Pump Pressure Test .................... 44
Cartridge Coil Activation Test .... 45
Hydraulic System Test ................ 46
Relief Valve Inspection and
Adjustment .................................. 47
Pilot-Operated Check Valve
Inspection .................................... 48
Introduction
How to Use the
Troubleshooting Guide
This guide consists of a series of
tables, diagrams, flowcharts and other
information. When used properly it
helps the mechanic to identify and
repair faulty system components.
Fisher Engineering recommends using
the Electrical Tester as a timesaving
tool for electrical system diagnosis.
When using this tester, refer to the
supplied instruction manual.
When diagnosing the snowplow
electrical and hydraulic systems,
some conditions must be eliminated
in order to develop valid tests. These
conditions are listed before the tables
or flowcharts and must be satisfied
before proceeding.
If the listed conditions are not met,
the procedure can result in inaccurate
results and wasted time.
All malfunctions of the snowplow can
be categorized as mechanical,
electrical, or hydraulic. Mechanical
issues are generally related to the
blade or attachments and can usually
be identified by visual inspection.
However, electrical and hydraulic
issues can be difficult to trace to the
component level and that is the
purpose of this troubleshooting guide.
In many cases, satisfying the listed
conditions alone solves the problem.
1. Go to the General Diagnostic
Table and satisfy the nine listed
conditions. These conditions
must be met before proceeding
into the table or to any subsequent
test.
Individual Solenoid Coil Test .... 49
Solenoid Cartridge Valve
Inspection .................................... 49
Vehicle Headlamp Test .............. 50
Snowplow Headlamp Test ......... 54
Vehicle Daytime Running
2. Locate the condition in the table
which best describes the problem
and check possible causes and
actions in the order listed.
Read and understand the Theory
of Operation before attempting
troubleshooting.
3. Proceed to a service procedure,
another condition, or a specific
test as directed. All tests except
the Hydraulic System Test use a
Lamps Test .................................. 65
Snowplow Daytime Running
Lamps Test .................................. 66
Lit. No. 27179
33
flowchart format. To use these
flowcharts, first satisfy any listed
conditions at the top of the page.
Then begin at the upper left square
and proceed as directed.
4. Follow along sequentially through
the table and tests, referring to the
hydraulic and electrical
schematics in the Theory of
Operation section and the
component Identification and
Location diagrams. Eventually the
problem is identified at the
component level.
Electrical Testing
Read and understand the Theory of
Operation section. A simple 12V test
light with a ground lead can be used
for circuit testing. When directed to
check for 12 volts (12V), ground the
test lamp lead and probe the terminal.
When asked to check for ground,
attach the test lamp lead to +12V and
probe the terminal. Note that 12V is a
nominal value. If using a voltmeter,
actual voltage will vary with the vehicle
and the presence of loads in tested
circuits. Continuity alone does not
guarantee a good circuit. Poor
connectors or damaged wires may
have continuity but be unable to carry
sufficient current.
July 2001
GENERAL DIAGNOSTIC TABLE
BEFORE USING THIS GENERAL DIAGNOSTIC TABLE, OR PERFORMING ANY TESTS, YOU MUST VERIFY THE FOLLOWING
CONDITIONS:
1. Snowplow is attached to vehicle
and all harnesses are connected.
2. Harness connector pins and
terminals are free of corrosion,
ensuring good connections, and
coated with dielectric grease.
4. Hydraulic reservoir is filled to fill
plug level with recommended fluid
when lift cylinder is fully retracted.
See Product Specifications.
CAUTION
Do not mix different types of
hydraulic fluid. Some fluids
are not compatible and may
cause performance problems
and product damage.
5. No oil leaks from hoses, fittings,
cylinders or the hydraulic unit.
7. FISHER® vehicle control harness
fuses are good.
8. Ignition is turned on or engine is
running.
9. The control is connected in the
cab and turned on.
6. All built up snow and ice is
removed from the snowplow.
3. Vehicle battery and charging
system are in good condition and
battery connections are clean and
tight.
CONDITION
POSSIBLE CAUSE
ACTION
Motor does not run for any requested function.
Poor connection of vehicle’s or plow’s battery cable.
Motor relay inoperative.
Defective control.
Fault in vehicle control harness.
Motor worn or damaged or pump seized.
Tighten and/or clean connections.
Go to Motor Relay Test.
Go to Control Test.
Go to Vehicle Control Harness Test.
Go to Motor Test.
Motor runs continuously.
Motor relay sticking or always energized.
Defective control.
Fault in vehicle control harness.
Go to Motor Relay Test.
Go to Control Test.
Go to Vehicle Control Test.
Snowplow won’t raise—motor runs.
Lift cylinder packing nut too tight.
Clogged pump filter (all functions are affected). *
Worn or damaged pump.
Adjust lift cylinder packing nut.
Clean or replace filter, flush reservoir.
Go to Pump Pressure Test.
* Thread sealant/tape is not compatible with hydraulics.
Lit. No. 27179
34
July 2001
GENERAL DIAGNOSTIC TABLE
CONDITION
POSSIBLE CAUSE
ACTION
Snowplow won’t raise—motor runs.
Solenoid valve coils not energizing properly.
Hydraulic system malfunction. *
Defective control.
Go to Cartridge Coil Activation Test.
Go to Hydraulic System Test.
Go to Control Test.
Snowplow raises slowly or partially—motor runs.
Poor connection of vehicle’s or plow’s cables.
Clogged pump filter (all functions are affected). *
Worn or damaged pump.
Clean and re-attach all connections.
Clean or replace filter, flush reservoir.
Go to Pump Pressure Test.
Snowplow will not lower or lowers slowly, or won’t
float.
Lift cylinder packing nut too tight.
Solenoid valve coils not activating properly.
Hydraulic system malfunction. *
Defective control.
Adjust lift cylinder packing nut.
Go to Cartridge Coil Activation Test.
Go to Hydraulic System Test.
Go to Control Test.
Snowplow lowers by itself or won’t stay in raised
position.
Hydraulic system malfunction. *
Defective control.
Go to Hydraulic System Test.
Go to Control Test.
Blade will not hold angled position.
Air in angle cylinders.
Oil bypassing crossover relief valve.
Hydraulic system malfunction. *
Cycle angle functions to purge cylinders.
Go to Relief Valve Inspection and Adjustment.
Go to Hydraulic System Test.
Snowplow does not perform the selected function or
performs a different function.
Hydraulic hose routing incorrect.
Verify correct hose installation. See Hose Routing
Diagram.
Go to Cartridge Coil Activation Test.
Go to Hydraulic System Test.
Go to Control Test.
Solenoid valve coils not energizing properly.
Hydraulic system malfunction. *
Defective control.
* Thread sealant/tape is not compatible with hydraulics.
Lit. No. 27179
35
July 2001
GENERAL DIAGNOSTIC TABLE
CONDITION
®
FISHER vehicle control harness control fuse blows.
POSSIBLE CAUSE
ACTION
Red wire in vehicle harness is shorted to ground.
Motor relay primary coil shorted internally.
Repair wire or replace vehicle harness.
Check primary coil with ohmmeter. Replace
defective motor relay.
Go to Individual Solenoid Coil Test. Replace
shorted coils.
Repair wire or replace vehicle harness.
Solenoid valve coil shorted internally.
Motor relay or solenoid coil wires in vehicle harness
shorted to ground.
Solenoid coil wires in snowplow harness shorted to
ground.
Defective control.
Repair wire or replace snowplow harness.
Go to Control Test.
Vehicle accessory fuse blows.
Circuit overloaded.
Consult vehicle owner’s manual for correct
application of aftermarket electrical loads.
Excessive load on vehicle electrical system
while using snowplow.
Pump Relief incorrectly adjusted.
Worn or damaged motor or pump.
Poor connection of battery cables.
Go to Pump Pressure Test.
Go to Pump Pressure Test.
Inspect battery cables, clean and re-establish all
battery connections.
Snowplow headlamps operate irregularly or not at all
–snowplow attached.
-orVehicle headlamps operate irregularly or not at all –
snowplow removed.
Burned out bulbs or corroded sockets.
Wires improperly located in connector inserted into
Isolation Module.
Replace bulbs, clean contacts.
Review and correct wire installation.
Go to Snowplow Headlamp Test.
Isolation Module improperly connected.
Go to Isolation Module Test.
Vehicle daytime running lamps (DRLs) do not work.
Parking brake on, vehicle not in drive. Light
sensor not deactivated.
Power in DRL circuit has been interrupted.
Fully release parking brake, place vehicle in drive.
Place light by sensor.
Turn lamp and/or ignition switch on and off to cycle
the DRL circuitry. Go to Vehicle DRL Test.
Snowplow DRLs do not work.
Power in DRL circuit has been interrupted.
Go to Snowplow DRL Test.
Blade will not hold position.
Hydraulic system malfunction.
Go to Hydraulic System Test.
Lit. No. 27179
36
July 2001
ANGLE AND LIFT CYLINDERS
Cylinder with Packing Nut
If equipped with this type of cylinder,
periodically verify the lift or angle
cylinder packing nuts have not
loosened. If a packing nut is loose or
leakage appears when activating the
cylinder, tighten the packing nut 1/4turn after you feel the packing nut
contact the packing.
If adjustment fails to stop fluid loss,
replacement of packing and/or rod (if
the chromed surface is pitted) may be
required.
Low Friction Cylinder
CAUTION
Do not overtighten the packing
nut. Overtightening affects the
operation and life of the
packing.
If equipped with this type of lift or
angle cylinder, the gland nut is
torqued to 150-180 ft-lbs at the
factory. Fluid leakage past the internal
seal to the outside indicates a bad
seal and/or that chromed rod is pitted.
Replacement of the damaged parts is
required.
NOTE: A small amount of leakage
is acceptable to properly lubricate
the rod.
Split Bearing
Rod Assembly
(includes Split Bearing)
Washer
Packing Set
Packing Nut
Wiper
Barrel
Lit. No. 27179
37
July 2001
MOTOR TEST
Refer to the Motor and Motor Relay
Test Diagram.
WARNING
The driver shall keep
bystanders clear of the blade
during this test. Do not stand
between the vehicle and the
blade. A moving or falling
blade could cause personal
injury.
Refer to the Motor and Motor Relay
Test Diagram.
To activate the motor, the following
conditions must be met:
YES
4.
+12V from the battery must be
connected to one secondary
terminal of the motor relay.
3. The vehicle lighting harness is
plugged into position 2 of the
Isolation Module.
5. The vehicle ignition switch must be
in the ON position.
6. The control must be turned on.
1. All three (3) snowplow and vehicle
harnesses and cable assemblies
must be connected.
MOTOR DOES NOT RUN
Are snowplow
and vehicle harnesses
properly connected?
2. The vehicle control harness is
plugged into position 1 of the
Isolation Module.
Are motor connections correct
(black/red stripe to positive terminal
and black to negative terminal)?
YES
When the control is activated
(raise, left, or right) is 12 volts on
the positive motor terminal?
YES
NO
NO
NO
Connect the snowplow
and vehicle harnesses
and cable assemblies.
Correct the
motor connections.
When the control is activated, is 12 YES
volts on the switched terminal of
the motor relay?
Is the vehicle cable
assembly black wire
connected to the negative
battery terminal?
YES
Check motor brushes,
check for damaged or
seized pump.
NO
Connect to negative
battery terminal.
NO
Go to Motor Relay Test.
MOTOR RUNS CONTINUOUSLY
Disconnect the brown/red
stripe from the motor relay
primary terminal. Does
motor stop?
YES
Go to the Control Test.
NO
Replace the motor relay.
Lit. No. 27179
38
July 2001
MOTOR AND MOTOR RELAY TEST DIAGRAM
Motor Terminal
(-)
Motor Terminal
(+)
Red Cable
+
Black\Orange
Wires
Brown/Red Wire
Red Cable
-
Motor Relay
Secondary
Terminals
Black Cable
Black/Red
Cable
Black/Orange
Wire
Vehicle
Control
Harness
Black
Cable
Red
Cable
Vehicle Cable Assembly
Plow Cable Assembly
Motor Relay
Primary Terminals
Black/Orange Wire
Brown/Red Wire
Lit. No. 27179
39
July 2001
MOTOR RELAY TEST
1. Momentarily jump power and
ground directly from battery to
motor to verify that the motor runs.
Make final connection at the
motor.
WARNING
The driver shall keep
bystanders clear of the blade
during this test. Do not stand
between the vehicle and the
blade. A moving or falling
blade could cause personal
injury.
2. Refer to the Motor and Motor
Relay Test Diagram, and Vehicle
Harness and Vehicle Cable
Location Diagram.
Motor does not run
Momentarily attach a jumper
cable across the motor relay
secondary terminals.
Does motor run?
YES
NO
Attach a jumper wire from
battery (+) to motor relay
primary terminal with
brown/red wire.
Does motor run?
NO
Leave (+) jumper wire attached
and attach a ground jumper wire
from battery (-) to relay primary
terminal with black/orange or
orange/black wire.
Does motor run?
YES
NO
Go to Vehicle Harness Test Motor Relay. If OK, go to
Control Test.
Repair or replace red (+) cable
from battery to motor relay.
YES
Repair or replace
orange/black wire
between motor relay and
battery (-).
Replace motor relay.
Motor runs continuously
Disconnect brown/red wire
from motor relay primary
terminal. Does the motor
stop?
NO
Replace motor relay.
Lit. No. 27179
YES
Verify correct polarity of
cables from battery to
motor.
NO
Reverse leads or replace cable
if manufactured incorrectly.
YES
Go to Control Test.
40
July 2001
VEHICLE CONTROL HARNESS TEST
Perform the Motor Test and Motor
Relay Test first.
WARNING
The driver shall keep
bystanders clear of the blade
during this test. Do not stand
between the vehicle and the
blade. A moving or falling
blade could cause personal
injury.
2. The vehicle control harness is
plugged into position 1 of the
Isolation Module.
To check the Vehicle Control Harness,
the following conditions must be met:
3. The vehicle lighting harness is
plugged into position 2 of the
Isolation Module.
1. The snowplow and vehicle lighting
harnesses must be connected.
4. Disconnect the control in the cab.
No Power To The Control
YES
NO
Check for a blown fuse or a
faulty connection on the
unswitched terminal of the motor
NO
relay.
Is socket #3 of the
control plug grounded?
YES
With the ignition switch in the
ON position, are there 12
volts on pos. C of the # 1
connector of the Isolation
Module?
3
6
2
5
1
4
YES
Socket end view
NO
NO
Is 12 volts present on both sides
of the control fuse ?
White 6-Pin Connector
on vehicle control harness
(located in cab)
5. The vehicle ignition switch must be
in the ON position.
Is 12 volts on socket #1
of the control plug?
6. Refer to the 6-pin Connector
diagram. Test the vehicle side of
the connector in the cab as
follows.
YES
Are vehicle cable assembly and
vehicle control harness grounds
connected?
YES
Perform Control Test.
NO
Connect the grounds.
NO
Check switched accessory
lead connection.
Using the Isolation Module
Tester, perform the Isolation
Module Test
Lit. No. 27179
41
July 2001
VEHICLE CONTROL HARNESS TEST
Motor Relay Will Not Activate
Is control power LED on?
YES
NO
When control is activated (raise, left, or YES
right) is 12 volts on the motor relay primary
terminal (the brown/red wire)?
NO
Is ground on the second motor relay primary
terminal (the black/orange wire)?
YES
Perform
Motor Relay Test.
NO
Are vehicle cable assembly and vehicle
control harness grounds connected?
Go to Control Test.
YES
NO
Is 7.5-Amp control fuse
blown?
YES
Replace the fuse.
Connect the grounds.
NO
Do park/turn lights
function on snowplow?
YES
NO
Are vehicle cable assembly and
vehicle control harness grounds
connected?
NO
Using the Isolation Module Tester,
perform the
Isolation Module Test.
YES
Connect the grounds.
Lit. No. 27179
42
July 2001
CONTROL TEST
Fish-Stik® Hand-held Control or Joystick Solenoid Control
1. Disconnect the control in the cab
and remove to work bench.
2. Perform the Cab Control Test
using the Minute Mount® Electrical
Tester.
To Safely Handle Hand-Held PCB:
Do outputs match results of
Cab Control Test from Minute
Mount® Electrical Tester?
Solenoid Control:
Replace PCB or control assembly.
NO
Control is OK. Verify vehicle
control harness ground and
power source for red wire.
YES
Replace control or proceed by carefully
disconnecting white cord connector from PCB.
Test the cord for continuity according to
electrical schematics. Note internal connection
in the cord. Does continuity match schematic?
Printed circuit board (PCB) is
subject to damage from static
electricity. Follow instructions
below to safely handle PCB.
2. Place control on its left side and
remove right side of handle, leaving
the keypad/circuit board assembly
in left half.
3. Touch any grounded metal object
to discharge possible static
buildup.
Lit. No. 27179
Seat cord connector fully on
the PCB. Retest Control.
Hand-Held Control:
Follow handling instructions. Remove handle
half. Is the white cord connector fully seated on
the PCB?
YES
CAUTION
1. Disconnect the control in the cab
and remove to a workbench.
NO
NO
Replace coil cord.
YES
4. Remove keypad/circuit board
assembly from housing by only
touching the edges of the keypad/
circuit board assembly.
Replace PCB.
5. The keypad/circuit board
assembly can be handled safely
as long as contact with it is
maintained.
43
July 2001
PUMP PRESSURE TEST
1. Check fluid level.
WARNING
The tester shall keep
bystanders clear of the blade
during this test. Do not stand
between vehicle and the
blade. A moving or falling
blade could cause personal
injury.
2. Lower blade to the ground to
remove any pressure from the lift
cylinder.
3
Snowplow Type
Relief Valve
Approx. turns out
from fully seated
Pump Relief Pressure PSI
± 100 PSI
All Straight Blades
2½ – 2¾
1750
5. Activate the raise function with the
control and read the pump relief
pressure. The chart lists relief
valve settings.
Carefully disconnect the hose for
the base end of the lift cylinder at
the valve manifold block.
4. Using a suitable adapter fitting,
attach a 3000 psi pressure gauge
to the valve block fitting.
Does pump relief pressure
match value on chart?
NO
YES
Is the pressure zero?
NO
Adjust pump relief clockwise1/8 NO
turn to increase pressure. Did
pressure change?
YES
YES
Is motor amp draw greater than NO
190 amps when pump is on
relief?
Remove reservoir. Inspect
pickup tube and filter.
Suction side OK?
Adjust to chart value.
YES
Inspect pump relief valve for
damaged components or
contamination. Is pump relief
valve good? See pg. 47
NO
Replace Relief Valve and
Adjust.
YES
Remove pump.
Is pump O-ring damaged?
NO
Replace pump.
YES
YES
NO
Replace pump
o-ring. Reassemble and
adjust pressure
Repair or replace motor.
Remove and inspect pump
Clean or replace pickup tube
and filter.
Go to Hydraulic System
Test.
Lit. No. 27179
44
July 2001
CARTRIDGE COIL ACTIVATION TEST
1. Disconnect the red (+) battery
cable from the motor and
isolate it.
2. Remove solenoid valve cover.
3. Verify wires are properly attached
to solenoid coils. Refer to
Electrical Schematic and Solenoid
Cartridge Valve Identification and
Location Table at top right of this
page.
4. Activate the control for each
function and check for magnetic
pull at all three solenoid valve coils
using common screwdriver. Only
the coils designated as "ON" in
the table below should activate for
each function. After noting which
coils are energized, proceed to the
flow chart.
Vehicle
Angle Angle
Control
Wire Color
Raise Lower
Right
Left
Harness
Socket
S1
9
White/ Yellow
ON
*
*
*
S2
4
Light Green
ON
ON
S3
3
Light Blue
ON
ON
* S1 output is “ON” for all functions if control is in “FLOAT”. Press “RAISE”
button to cancel “FLOAT”.
Fish-Stik® Hand-Held Control Only – While in “FLOAT”, pressing and holding
the “RIGHT” or “LEFT” button turns off solenoid cartridge valve S1 until the
button is released.
Solenoid
Coil
3-Pin Connector
Snowplow Side
3
4
9
Do activated coils match the chart for
all functions?
YES
Go to Hydraulic System Test.
Lit. No. 27179
NO
Verify battery cables are connected. Is NO
ground at all black/orange wires attached
to coils?
YES
Repair black/orange wires to coils,
check ground connections at motor,
battery cable connector and battery (-)
terminal. Retest.
Using Minute Mount® Electrical Tester,
perform the Snowplow Harness Test.
45
July 2001
HYDRAULIC SYSTEM TEST
This test consists of trying all the
snowplow functions and comparing
the snowplow reaction to the action
requested in the following table. The
table will pinpoint faulty solenoid
valves or p/o check valve accurately if
only one component is malfunctioning.
If the snowplow reaction for a given
function is not listed in the table, there
may be a relief or p/o check valve
which is stuck open or contaminated,
missing or damaged o-rings or
backing rings on cartridge, relief or p/o
check valve, or there may be two or
more faulty components. In this case,
use the specific function hydraulic
schematic and carefully inspect each
component in the flow circuit. If
contamination is evident in more than
one component, the hydraulic unit,
hoses and cylinders must be
completely disassembled, inspected
and cleaned.
ACTION REQUESTED
Raise
Lower
1. Perform Cartridge Coil Activation
Test first.
2. Verify hydraulic hose installation is
correct. Refer to the Hydraulic
Hose Routing diagram.
3. Test all snowplow functions.
5. Refer to the sections following the
table for inspecting and adjusting
solenoid cartridge valves, p/o
check valve, and relief valves.
IMPORTANT: When testing the
snowplow functions, be sure the
control is not in “float.”
4. Inspect and clean or replace the
suspected component. Refer to
the Hydraulic Unit Parts Diagram.
PLOW REACTION
None
Angle Left
None
POSSIBLE CAUSE
S3 not shifted
S2 stuck shifted
S1 not shifted
S2 stuck shifted
S3 stuck shifted
Angle Right
Angle Left
None (blade raised)
None
Angle Left
None
Slow
Angle Right
Raise
None
Slow
Lowers
Drifts Right
S3 stuck shifted
S2 not shifted
Poppet check valve not opening
S3 not shifted
S2 not shifted
S2 and S3 not shifted
Poppet check valve not opening
S1 stuck shifted or has leaking internal check valve
S2 stuck shifted
Contamination, bad valve stem seat, or damaged O-rings
in crossover relief valve
Poppet check valve open
Contamination, bad valve stem seat, or damaged O-rings
in crossover relief valve
Drifts Left
Lit. No. 27179
46
July 2001
RELIEF VALVE INSPECTION AND ADJUSTMENT
Relief Valve Inspection
Adjustment
Hydraulic System
1. Remove the valve stem, ball,
spacer and spring.
1. Adjust by tightening the relief valve
stem until it bottoms out (until
spring is fully compressed).
2. Look for broken or damaged parts,
contamination or missing or
damaged O-rings.
2. Back off valve stem (rotate
counterclockwise) the number of
turns indicated in the chart.
Relief Valve
Pump Relief *
Angle Cylinder Crossover Relief
Regular (RD & HD)
Commercial (MC)
LD
CAUTION
Be careful to strike stem
squarely. You can bend stem if
you do not strike it squarely.
3. If parts are in good condition,
place ball on hard wood block,
hold stem seat on ball and lightly
strike top of stem with a hammer.
This seats the ball and valve stem.
4. Apply a light coat of anti-seize or
grease to stem threads. Lubricate
O-rings with hydraulic fluid.
Reassemble components into
valve block.
No. of Turns
Backed Off (CCW)
From Fully Seated
2½ – 2¾
Approximate Relief
Valve Pressure
± 100 (PSI)
1¼ – 1½
2¼ – 2½
2¼ – 2½
4000
2500
2500
1750
* See Pump Pressure Test to measure actual pump relief pressure.
Spring
Spring Spacer
Ball
O-Rings
Valve Stem
Lit. No. 27179
47
July 2001
PILOT-OPERATED (POPPET STYLE) CHECK VALVE INSPECTION
1. Strike boss plugs squarely with a
hammer to facilitate removal.
2. Remove O-ring boss plug, spring
and poppet.
3. Remove O-ring boss plug, spring
and spool with O-ring. Use long/
slender needle-nosed pliers to
remove spool.
4. Inspect springs, poppet, spool,
O-rings and poppet seat for wear,
damage or contamination.
5. If the valve manifold block has a
steel poppet seat, use a strong
pencil magnet to push and pull on
the seat. If the seat moves at all,
replace the valve block.
6. Re-oil O-rings, install spool fully
into bore. Spool must insert
smoothly.
Valve Manifold Block
O-Ring
Back-Up Ring
Poppet
Spool
Spring
Spring
O-Ring Boss Plug
O-Ring Boss Plug
7. Install poppet, springs and O-ring
boss plugs. Torque O-ring boss
plug to 60 in-lb.
Lit. No. 27179
48
July 2001
INDIVIDUAL SOLENOID COIL TEST
SOLENOID CARTRIDGE VALVE INSPECTION
1. Remove both wires from coil
terminals.
1. Remove coils from the solenoid
cartridge valves and remove
cartridge valves from manifold.
Look for visible contamination or
damaged seals. Check for stuck
spools with a plastic, aluminum, or
soft brass probe by pushing on the
spring-loaded internal spool from
the end of the valve. The spool
should move freely through its
entire travel.
2. Attach an ohmmeter across the
coil terminals.
3. A reading of approximately 7 ohms
indicates the coil is good. A good
coil draws approximately 1.5
amps.
NOTE: Using probe to move spool
may shear contamination which
was affecting spool movement.
cartridge valve, torquing to 10 ft-lb.
Install the coils and torque retaining
nuts to 4 ft-lb.
NOTE: If contamination is seen in
more than one component, it can
be reasonably assumed that the
entire system is contaminated and
in order to perform a proper
repair, the entire hydraulic unit
must be disassembled and
cleaned. The hoses and cylinders
must also be disassembled and
cleaned. The source of the
contamination must be located
and repaired before reassembly.
2. Bench test the cartridge valve by
installing a coil on the stem and
applying 12V and ground. Watch
through the side ports for internal
spool travel.
If the cartridge valve spool is stuck or
its travel is restricted, replace the
cartridge. If the cartridge valve is in
good condition, clean it with parts
cleaning solvent and dry with
compressed air, being careful not to
damage the seals. Check the spool
travel again in case any internal
contaminants were dislodged during
cleaning. Re-oil the cartridge valve
seals and o-rings and reinstall the
Apply 12V
and ground
to coil
Cartridge valve
identification
marked on hex
( SVO8– XXX)
Watch here
Probe here
Lit. No. 27179
49
July 2001
VEHICLE HEADLAMP TEST
Refer to Electrical Schematic.
To check the vehicle headlamps the
following conditions must be met:
1. FISHER® park, turn, and DRL
wires (if applicable) must be
connected.
3. The vehicle lighting harness is
plugged into position 2 of the
Isolation Module.
2. The vehicle control harness is
plugged into position 1 of the
Isolation Module.
4. The vehicle ignition switch must be
in the ON position.
NO LEFT LOW BEAM
Did vehicle left low beam
function before installing
plug-in harnesses?
YES
NO
NO
Troubleshoot the faulty vehicle
condition.
Do headlamps have a negative
or positive common?
Is left plug-in harness connected to position YES
4 of the Isolation Module?
POSITIVE
YES
NO
Connect to correct
Isolation Module connector.
NEGATIVE
Is plug-in harness connected to
vehicle left headlamp and/or
vehicle connector?
Disconnect plug-in harness from
position 3 of the Isolation Module. Turn
on the headlamps in the low beam
mode. Is 12 volts on position A of the
plug-in harness 10-pin connector?
Connect to proper connectors.
YES
Is ground on position K of the
plug-in harness 10-pin
connector?
YES
Is configuration plug installed and
confiured per instructions?
NOTE: 1999-20_GMC All New Sierra
and 1999-20_Chevy Silverado proceed
to positive headlamp test.
NO
Configure and install configuration
plug per instructions.
YES
YES
Using the Isolation Module
Tester, perform the
Isolation Module Test.
NO
NO
Disconnect plug-in harness from
position 3 of the Isolation Module.
Turn on the headlamps in the low
beam mode. Is 12 volts on
position K of the plug-in harness
10-pin connector?
NO
NO
YES
Is ground on position A of the
plug-in harness 10-pin
connector?
Check for faulty connection or a
misw ired headlamp connector. Check
for blow n vehicle headlamp fuse.
YES
Lit. No. 27179
50
July 2001
VEHICLE HEADLAMP TEST
NO RIGHT LOW BEAM
Did vehicle right low beam function
before installing plug-in harnesses?
YES
YES
NO
NO
Troubleshoot the faulty vehicle
condition.
Do headlamps have a negative
or positive common?
Is right plug-in harness connected to
position 4 of the Isolation Module?
POSITIVE
YES
NO
Connect to correct
Isolation Module connector.
NEGATIVE
Is plug-in harness connected to
vehicle right headlamp and/or
vehicle connector?
Disconnect plug-in harness from
position 4 of the Isolation Module. Turn
on the headlamps in the low beam
mode. Is 12 volts on position A of the
plug-in harness 10-pin connector?
Connect to proper connectors.
YES
Is ground on position K of the
plug-in harness 10-pin
connector?
YES
Using the Isolation Module
Tester, perform the
Isolation Module Test.
NO
NO
Disconnect plug-in harness from
position 4 of the Isolation Module.
Turn on the headlamps in the low
beam mode. Is 12 volts on
position K of the plug-in harness
10-pin connector?
NO
NO
Is ground on position A of the
plug-in harness 10-pin
connector?
Check for faulty connection or a
miswired headlamp connector. Check
for blown vehicle headlamp fuse.
YES
YES
Lit. No. 27179
51
July 2001
VEHICLE HEADLAMP TEST
NO LEFT HIGH BEAM
YES
Did vehicle left high beam function
before installing
plug-in harnesses?
NO
YES
Is plug-in harness connected to vehicle
left headlamp and/or vehicle connector?
NO
Troubleshoot the faulty
vehicle condition.
Do headlamps have a negative or
a positive common?
Is left plug-in harness connected to
position 3 of the Isolation module?
NO
Connect to proper connectors.
Connect to the correct Isolation Module
connector.
NEGATIVE
POSITIVE
Disconnect plug-in harness from
position 3 of Isolation Module. Turn on
headlamps in high beam mode. Is 12
volts on position B of the plug-in
harness 10-pin connector?
YES
YES
Is ground on position K of the plug-in
harness 10-pin connector?
YES
Using the Isolation Module
Tester, perform the
Isolation Module Test.
NO
NO
Disconnect plug-in harness from
position 3 of Isolation Module. Turn on
headlamps in high beam mode. Is
12 volts on position K of the plug-in
harness 10-pin connector?
NOTE: Dodge Rams equipped with
sport package (HB1 and HB5
headlamps) must also check for
ground on position C.
NO
NO
Check for faulty connection or a
miswired headlamp connector. Check
for blown vehicle headlamp fuse.
Is ground on position B of the plug-in
harness 10-pin connector?
YES
YES
Lit. No. 27179
52
July 2001
VEHICLE HEADLAMP TEST
NO RIGHT HIGH BEAM
Did vehicle right high beam function
before installing plug-in
harnesses?
YES
NO
NEGATIVE
Disconnect plug-in harness from
position 4 of the Isolation Module. Turn
on the headlamps in the high beam
mode. Is 12 volts on position B of the
plug-in harness 10-pin connector?
Is the plug-in harness connected to the YES
vehicle right side headlamp and/or vehicle
connector?
NO
Connect to the correct
Isolation Module connector.
POSITIVE
Disconnect plug-in harness from
position 4 of the Isolation Module.
Turn on the headlamps in the high
beam mode. Is 12 volts on position
K?
NOTE: Dodge Rams equipped w ith
sport package (HB1 and HB5
headlamps) must also check for
ground on position C of the plug-in
harness 10-pin connector.
YES
NO
Troubleshoot the faulty
vehicle condition.
Do headlamps have a negative
or a positive common?
Is right plug-in harness connected to
position 4 of the
Isolation module?
Connect to proper connectors.
YES
Is ground on position K of the plug-in
harness 10-pin connector?
YES
Using the Isolation Module
Tester, perform the
Isolation Module Test.
NO
NO
NO
NO
Check for faulty connection or a
misw ired headlamp connector. Check
for blow n vehicle headlamp fuse.
Is ground on position B of the plug-in
harness 10-pin connector?
YES
YES
Lit. No. 27179
53
July 2001
SNOWPLOW HEADLAMP TEST
Refer to Electrical Schematic.
1. All vehicle lights must be
functioning correctly with the
Isolation Module installed. If the
vehicle lights are not functioning
correctly, run the Vehicle
Headlamp Test before proceeding.
To check the snowplow headlamps
the following conditions must be met:
NO LEFT LOW BEAM
Is the snowplow lighting harness
connected to the vehicle lighting
harness at the grille?
YES
NEGATIVE
POSITIVE
Go to A
Using the Isolation Module Tester,
perform Isolation Module Test.
Replace vehicle lighting harness.
Is the black/orange ground wire from the YES
vehicle cable assembly connected to
the vehicle control harness?
Is the vehicle cable assembly black wire YES
connected to the negative side of the
battery?
NO
Remove headlamp bezel. Turn YES
on
headlamps in the low beam mode. Is
12 volts on the black wire from the
headlamp plug?
YES
Is ground on the light blue wire from
the headlamp plug?
YES
Connect the black/orange ground
wires together.
YES
Replace the sealed beam.
NO
NO
YES
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position B of the 10-pin connector and
the black wire on the headlamp plug?
Disconnect vehicle lighting harness
from position 2 of Isolation Module.
Is there continuity between position J
of the 10-pin connector and the light
blue wire on the headlamp plug?
NO
YES
YES
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 6 of the snowplow lighting
harness plug and the black wire on
the headlight connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between pin
11 of the snowplow lighting harness
plug and light blue wire of the
headlamp connector?
NO
YES
Replace vehicle lighting harness.
NO
Replace snowplow lighting harness.
Lit. No. 27179
Is the black/orange ground wire from
the vehicle control harness and the
vehicle lighting harness connected?
NO
Connect the black/orange ground wires
together.
Connect the black wire to the negative
battery terminal.
Connect both harnesses together.
4. The vehicle ignition switch must be
in the ON position.
3. The snowplow lighting harness
must be connected to the vehicle
lighting harness.
NO
NO
Do headlamps have a negative or
a positive common?
2. FISHER® park, turn, and DRL
wires (if applicable) must be
connected.
Replace snowplow lighting harness.
54
July 2001
SNOWPLOW HEADLAMP TEST
NO LEFT LOW BEAM, CONTINUED
A
POSITIVE
YES
Remove headlamp bezel. Turn on
headlamps in low beam mode. Is
there ground on the black wire from
the headlamp plug?
YES
YES
NO
NO
Using the Isolation Module Tester,
perform Isolation Module Test.
YES
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position J of 10-pin connector and
light blue wire on the headlamp
plug?
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position B of the 10-pin connector and
the black wire on the headlamp plug?
YES
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 6 of the snowplow lighting
harness plug and the black wire on
the headlamp connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between pin
11 of the snowplow lighting harness
plug and the light blue wire on the
headlamp connector?
Using the Isolation Module Tester,
perform Isolation Module Test.
YES
Replace vehicle lighting harness.
NO
NO
Replace snowplow lighting harness.
Replace snowplow lighting harness.
Lit. No. 27179
YES
NO
NO
Replace vehicle lighting harness.
Replace the sealed beam.
Is 12 volts on the light blue wire from
the headlamp plug?
55
July 2001
SNOWPLOW HEADLAMP TEST
NO RIGHT LOW BEAM
Is the snowplow lighting harness
connected to the vehicle lighting
harness at the grille?
YES
NEGATIVE
POSITIVE
Go to B
YES
Remove headlamp bezel. Turn on
headlamps in the low beam mode. Is
12 volts on the black/white wire from
the headlamp plug?
YES
YES
NO
YES
Is ground on the blue/orange wire
from the headlamp plug?
Replace the sealed beam.
NO
NO
YES
Disconnect vehicle lighting harness
from position 2 of the Isolation Module.
Is there continuity between position E
of the 10-pin connector and the
black/white wire on the headlamp
plug?
Disconnect vehicle lighting harness
from position 2 of Isolation Module. Is
there continuity between position K of
the 10-pin connector and the
blue/orange wire on the headlamp
plug?
YES
YES
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 1 of the snowplow lighting
harness plug and the black/white
wire on the headlamp connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between pin
5 of the snowplow lighting harness
plug and the blue/orange wire on the
headlamp connector?
NO
YES
Replace vehicle lighting harness.
NO
Replace snowplow lighting harness.
Lit. No. 27179
Is the black/orange ground wire from
the vehicle control harness and the
vehicle lighting harness connected?
Connect the black/orange ground
wires together.
Connect the black/orange ground wires
together.
NO
Replace vehicle lighting harness.
YES
NO
Connect the black wire to the negative
battery terminal.
Connect both harnesses together.
Using the Isolation Module Tester,
perform Isolation Module Test.
Is the black/orange ground wire from the
vehicle cable assembly connected to
the vehicle control harness?
NO
NO
Do headlamps have a negative or
a positive common?
Is the vehicle cable assembly black wire YES
connected to the negative side of the
battery?
Replace snowplow lighting harness.
56
July 2001
SNOWPLOW HEADLAMP TEST
NO RIGHT LOW BEAM, CONTINUED
B
POSITIVE
YES
Remove headlamp bezel. Turn on
headlamps in the low beam mode. Is
there ground on the black/white wire
from the headlamp plug?
YES
YES
Is 12 volts on the blue/orange wire
from the headlamp plug?
Replace the sealed beam.
NO
NO
Using the Isolation Module Tester,
perform Isolation Module Test.
YES
Disconnect vehicle lighting harness
from position 2 of the Isolation Module.
Is there continuity between position E
of the 10-pin connector and the
black/white wire on the headlamp
plug?
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position K of 10-pin connector and
blue/orange wire on the headlamp
plug?
NO
Replace vehicle lighting harness.
YES
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between pin
1 of the snowplow lighting harness
plug and the black/white wire on the
headlamp connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between pin
5 of the snowplow lighting harness
plug and the blue/orange wire on the
headlamp connector?
NO
YES
Replace vehicle lighting harness.
NO
Replace snowplow lighting harness.
Lit. No. 27179
YES
Replace snowplow lighting harness.
57
July 2001
SNOWPLOW HEADLAMP TEST
NO LEFT HIGH BEAM
Is the snowplow lighting harness
connected to the vehicle lighting
harness at the grille?
YES
NO
NO
NEGATIVE
POSITIVE
Go to C
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
Connect the black wire to the negative
battery terminal.
Connect both harnesses together.
Do headlamps have a negative or
a positive common?
Is the black/orange ground wire from the YES
vehicle cable assembly connected to
the vehicle control harness?
Is the vehicle cable assembly black wire YES
connected to the negative side of the
battery?
YES
Remove headlamp bezel. Turn on
headlamps in the high beam mode.
Is 12 volts on the white wire from the
headlamp plug?
YES
Replace the sealed beam.
NO
NO
YES
Disconnect vehicle lighting harness
from position 2 of Isolation Module.
Is there continuity between position J
of the 10-pin connector and the light
blue wire on the headlamp plug?
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position A of the 10-pin connector and
the white wire on the headlamp plug?
YES
YES
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 4 of the snowplow lighting
harness plug and the white wire on
the headlamp connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between pin
11 of snowplow lighting harness plug
and the light blue wire on the
headlamp connector?
YES
Replace vehicle lighting harness.
NO
NO
Replace snowplow lighting harness.
Lit. No. 27179
Connect the black/orange ground
wires together.
Is ground on the light blue wire from
the headlamp plug?
NO
Replace vehicle lighting harness.
YES
NO
Connect the black/orange ground wires
together.
YES
Is the black/orange ground wire from
the vehicle control harness and the
vehicle lighting harness connected?
Replace snowplow lighting harness.
58
July 2001
SNOWPLOW HEADLAMP TEST
NO LEFT HIGH BEAM, CONTINUED
C
POSITIVE
YES
Remove headlamp bezel. Turn on
headlamps in the high beam mode.
Is there ground on the white wire
from the headlamp plug?
YES
YES
Is 12 volts on the light blue wire from
the headlamp plug?
Replace the sealed beam.
NO
NO
Using the Isolation Module Tester,
perform Isolation Module Test.
YES
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position A of the 10-pin connector and
the white wire on the headlamp plug?
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position J of 10-pin connector and
light blue wire on the headlamp plug?
YES
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 4 of the snowplow lighting
harness plug and the white wire on
the headlamp connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between pin
11 of the snowplow lighting harness
plug and the light blue wire on the
headlamp connector?
YES
Replace vehicle lighting harness.
NO
NO
Replace snowplow lighting harness.
Replace snowplow lighting harness.
Lit. No. 27179
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
NO
Replace vehicle lighting harness.
YES
59
July 2001
SNOWPLOW HEADLAMP TEST
NO RIGHT HIGH BEAM
Is the snowplow lighting harness
connected to the vehicle lighting
harness at the grille?
YES
NEGATIVE
POSITIVE
Go to D
YES
Remove headlamp bezel. Turn on
headlamps in the high beam mode.
Is 12 volts on the white/yellow wire
from the headlamp plug?
Connect the black/orange ground
wires together.
YES
YES
Is ground on the blue/orange wire
from the headlamp plug?
Replace the sealed beam.
NO
NO
YES
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position D of the 10-pin connector and
the white/yellow wire on the
headlamp plug?
Disconnect vehicle lighting harness
from position 2 of Isolation Module.
Is there continuity between position
K of the 10-pin connector and the
blue/orange wire on the headlamp
plug?
YES
YES
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 3 of the snowplow lighting
harness plug and the white/yellow
wire on the headlamp connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 5 of snowplow lighting harness
plug and the blue/orange wire on the
headlamp connector?
NO
YES
Replace vehicle lighting harness.
NO
Replace snowplow lighting harness.
Lit. No. 27179
YES
NO
Connect the black/orange ground wires
together.
NO
Replace vehicle lighting harness.
Is the black/orange ground wire from
the vehicle control harness and the
vehicle lighting harness connected?
NO
Connect the black wire to the negative
battery terminal.
Connect both harnesses together.
Using the Isolation Module Tester,
perform Isolation Module Test.
Is the black/orange ground wire from the
vehicle cable assembly connected to
the vehicle control harness?
NO
NO
Do headlamps have a negative or
a positive common?
Is the vehicle cable assembly black wire YES
connected to the negative side of the
battery?
Replace snowplow lighting harness.
60
July 2001
SNOWPLOW HEADLAMP TEST
NO RIGHT HIGH BEAM, CONTINUED
D
POSITIVE
YES
Remove headlamp bezel. Turn on
headlamps in the high beam mode.
Is ground on the white/yellow wire
from the headlamp plug?
YES
YES
Is 12 volts on the blue/orange wire
from the headlamp plug?
Replace the sealed beam.
NO
NO
Using the Isolation Module Tester,
perform Isolation Module Test.
YES
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position D of the 10-pin connector and
the white/yellow wire on the headlamp
plug?
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position K of 10-pin connector and
blue/orange wire on the headlamp
plug?
NO
Replace vehicle lighting harness.
YES
Using the Isolation Module Tester,
perform Isolation Module Test.
NO
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 3 of the snowplow lighting
harness plug and the white/yellow
wire on the headlamp connector?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. Is there continuity between
pin 5 of the snowplow lighting
harness plug and the blue/orange
wire on the headlamp connector?
YES
Replace vehicle lighting harness.
NO
NO
Replace snowplow lighting harness.
Lit. No. 27179
YES
Replace snowplow lighting harness.
61
July 2001
SNOWPLOW HEADLAMP TEST
NO LEFT
SNOWPLOW TURN
SIGNAL LAMPS
Is snowplow lighting harnessYES
connected to the vehicle lighting
harness at the grille?
Is the BLK/ORN wire from the plow
lighting harness connected to the
negative motor terminal?
YES
Is plow cable
Assy.
YES
connected
to vehicle cable
Assy. at grille ?
YES
NO
NO
Connect both
cable assemblies.
Connect both harnesses together.
YES
Is ground on BLK/ORN wire
connected to the Park/Turn bulb
assemblies?
YES
Remove left headlamp bezel. Is
there continuity between neg. motor
terminal and Park/Turn socket
mounting plate?
NO
Is snowplow Park/Turn fuse blown?
NO
Connect black
wire to neg.
battery terminal.
Are the Park/Turn bulbs seated
correctly?
Connect BLK/ORN ground wire
together
YES
YES
Use Isolation Module Tester to
perform Isolation Module Test
NO
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position G of the 10-pin connector
and the junction of the gray and red
wires?
Disconnect snowplow lighting and
vehicle lighting harnesses at the grille.
On the snowplow lighting harness, is
there continuity between position 8 of
the snowplow lighting harness plug and
the junction of the gray and red wires?
Replace snowplow lighting harness
YES
Is there continuity from Position G of
the 10-pin connector to the left turn
signal tap?
NO
Replace vehicle lighting harness.
NO
YES
YES
On the vehicle lighting harness, is
there continuity between pin 7 of the
vehicle lighting harness plug and
Pin C of the 10-pin Isolation Module
connector?
Disconnect the plug-in harness from
Pos. 3 of the Isolation Module. Is there
12 volts on Pos.G of the plug –in
harness 10-pin connector? When the
left turn signal is activated?
NO
NO
YES
Tighten ground screw on Park/Turn
Bulb Assy.
YES
Replace defective bulbs.
Remove and re-install the Park/Turn
bulbs.
YES
Replace fuse.
YES
NO
NO
NO
Is BLK/ORN wire from vehicle YES
control harness and vehicle lighting
harness connected?
YES
YES
NO
NO
Connect BLK/ORN wire to the neg.
side of the motor terminal.
Remove left headlamp bezel.
Activate the vehicle’s left turn
signal. Is 12 volts present at the
junction of the gray and red wires?
Is vehicle cable
YES
Assy. BLK wire
connected to
Neg. side of
battery?
YES
On the vehicle lighting harness is
there continuity between pin 2 of the
vehicle lighting harness and the
negative terminal of the battery?
NO
Check all ground connections.
NO
YES
Check turn signal tap. Check
vehicle turn signal circuit to ensure
it is working correctly.
NO
On the vehicle lighting harness, is there
continuity between Position G of the 10-pin
connector and Position 8 of the vehicle
lighting harness plug?
Replace snowplow plug-in harness.
NO
Lit. No. 27179
62
July 2001
SNOWPLOW HEADLAMP TEST
NO RIGHT
SNOWPLOW TURN
SIGNAL LAMPS
Is snowplow lighting harnessYES
connected to the vehicle lighting
harness at the grille?
Is the BLK/ORN wire from the
plow lighting harness connected
to the negative motor terminal?
YES
NO
Is plow cable
Assy. connected
to vehicle cable
Assy. at grille?
YES
NO
Connect both harnesses
together.
NO
Connect BLK/ORN wire to the
neg. side of the motor terminal.
Remove left headlamp bezel.
Activate the vehicle’s left turn
signal. Is 12 volts present at the
junction of the gray and red
wires?
YES
Is ground on BLK/ORN wire
connected to the Park/Turn bulb
assemblies?
Connect both
cable assemblies.
YES
Remove right headlamp bezel.
Is there continuity between neg.
motor terminal and Park/Turn
socket mounting plate?
NO
Is snowplow fuse blown?
NO
Are the Park/Turn bulbs seated
correctly?
Disconnect snowplow lighting and
vehicle lighting harnesses at the
grille. On the snowplow lighting
harness, is there continuity between
position 9 of the snowplow lighting
harness plug and the junction of the
purple and red wires?
YES
Replace Snowplow Lighting Harness
Lit. No. 27179
Replace defective bulbs.
YES
On the vehicle lighting harness,
is there continuity between pin 7
of the vehicle lighting harness
plug and Pin C of the 10-pin
Isolation Module connector?
NO
YES
Replace Vehicle Lighting
Harness.
On the vehicle lighting harness
is there continuity between pin 2
of the vehicle lighting harness
and the negative terminal of the
battery?
NO
Check all ground connections.
NO
Is there continuity from Position G
of the 10-pin connector to the right
turn signal tap?
YES
Check turn signal tap. Check
vehicle turn signal circuit to
ensure it is working correctly.
NO
YES
NO
YES
Use Isolation Module Tester to
perform Isolation Module Test
Disconnect the plug-in harness
from Pos. 4 of the Isolation
Module. Is there 12 volts on Pos.G
of the plug –in harness 10-pin
connector? When the vehicle right
turn signal is activated?
NO
Connect BLK/ORN ground
wires together.
YES
Tighten ground screw on
Park/Turn Bulb Assy.
YES
YES
Remove and re-install the
Park/Turn bulbs.
NO
Disconnect vehicle lighting
harness from position F of the
Isolation Module. Is there
continuity between position F of
the 10-pin connector and the
purple and red wires?
Is BLK/ORN wire from vehicle
YES
control harness and vehicle
lighting harness connected?
NO
Connect black
wire to neg.
battery terminal.
YES
Replace fuse.
YES
NO
NO
NO
YES
Is vehicle cable
Assy. BLKYES
wire
connection to Neg.
side of batt?
On the vehicle lighting harness, is there
continuity between position G of the 10-pin
connector and position 8 of vehicle lighting
harness plug?
Replace Snowplow plug-in harness.
NO
63
July 2001
SNOWPLOW HEADLAMP TEST
NO SNOWPLOW PARKING LIGHTS
Is snowplow lighting harness connected
to vehicle lighting harness at the grille?
YES
Is BLK/ORN wire from the plow lighting
harness connected to the the negative
motor terminal?
NO
NO
YES
Is ground on the black/orange wire
connected to the park/turn bulb
assemblies?
YES
NO
Disconnect vehicle lighting harness
from position 2 of the Isolation
Module. Is there continuity between
position H of the 10-pin connector and
the brown wires of the headlamp
assemblies?
Replace snowplow lighting harness.
YES
Are park/turn bulbs seated correctly?
Lit. No. 27179
NO
YES
Connect black/orange ground wires
together.
YES
Replace defective bulbs.
NO
YES
YES
Using the Isolation Module Tester,
perform the Isolation Module Test.
NO
Check, clean and tighten ground
connections on the park/turn socket
mounting plate and on the neg.
motor terminal .
Disconnect the short plug-in harness
from the Isolation Module. Is there
continuity from position H of the plugin harness 10-pin connector to the
park light tap?
YES
Disconnect the snowplow lighting
and vehicle lighting harnesses at the
grille. On vehicle lighting harness is
there continuity between pin 7 of the
vehicle lighting harness and pin c of
the 10-pin Isolation
NO Module
connector?
YES
NO
Replace vehicle lighting harness.
Is black/orange ground wire from
vehicle control harness and vehicle
lighting harness connected?
NO
Replace fuse.
Remove headlamp bezel. Check
continuity between neg. motor
terminal and park/turn socket
mounting plates.
NO
Disconnect snowplow lighting and
vehicle lighting harnesses at the grille.
Is there continuity between pin 10 of
the snowplow lighting harness plug and YES
the brown wires of the headlamp
assemblies?
NO
YES
Remove and reinstall park/turn
bulbs.
NO
Is snowplow park/turn fuse blown?
YES
Is vehicle cable
assy. BLK wire
connected to Neg.
side of battery?
NO
NO
Connect black/orange Connect black wire to
ground wires together. neg. battery terminal.
Connect black/orn wire to
negative battery terminal.
Connect both harnesses together.
Remove headlamp bezels. Place the
headlamp switch in the park lamp
position. Is 12 volts on the junction of
the brown wires?
Is plow cable
assy. connected
to vehicle cable
assy. at grille ?
YES
NO
Replace plug-in harness.
Replace vehicle lighting harness.
64
YES
On the vehicle lighting harness is
there continuity between pin 2 of the
vehicle lighting harness and the
negative terminal of the battery?
NO
Check all ground connections.
July 2001
VEHICLE DAYTIME RUNNING LAMPS (DRL) TEST
To check the vehicle DRL system, the
following conditions must be met:
1. Fully understand the operation of
the vehicle DRL system before
attempting to troubleshoot DRL
problems on the snowplow.
3. The Isolation Module and the
associated harnesses have been
installed using the installation
instructions provided.
2. All vehicle lighting systems must
be functioning correctly before the
Isolation Module is installed.
4. FISHER® DRL wires (if applicable)
must be connected.
5. The vehicle ignition switch must be
in the ON position.
NO VEHICLE DRLS
YES
Is left plug-in harness
connected to position 3 of the
Isolation Module?
Is the plug-in harness
connected to the vehicle left
headlamp(s) and/or vehicle
connector(s)?
NO
YES
YESIs right plug-in harness
connected to position 4 of the
Isolation Module?
NO
Connect to correct Isolation
Module connector.
YES
Is plug-in harness connected YES
to vehicle right headlamp(s)
and/or vehicle connector(s)?
NO
Connect to the proper
connectors.
Is configurationYES
plug
jumpered correctly?
negative common – jumper B to A
positive common – jumper B to C
NOTE: 1999-20_ GMC All New Sierra and
1999-20_ Chevy Silverado do not require a
configuration plug. The vehicle DRLs do not
turn off when the snowplow is attached.
YES
Are the beams used for the
Daytime Running Lamps
working properly during
normal headlamp operation?
YES
NO
NO
Connect to correct Isolation
Module connector.
Connect to the proper
connectors.
Is the vehicle DRL fuse
blown?
YES
YES
Is vehicle control harness
connected to position 1 of
the Isolation Module?
Connect to correct Isolation
Module connector.
Replace the fuse.
NO
NO
NO
Configure plug for the correct headlamp
common.
Lit. No. 27179
Replace any defective bulb(s)
and then, using the Isolation
Module Tester, perform the
Isolation Module Test.
Investigate vehicle DRL
system.
65
July 2001
SNOWPLOW DAYTIME RUNNING LAMPS (DRL) TEST
To check the snowplow DRL system,
the following conditions must be met:
1. Fully understand the operation of
the vehicle DRL system before
attempting to troubleshoot DRL
problems on the snowplow.
3. FISHER® DRL wires (if applicable)
must be connected.
4. The vehicle ignition switch must be
in the ON position.
2. All vehicle lighting systems must
be functioning correctly before the
Isolation Module is installed.
NO SNOWPLOW DRLS
Is snowplow lighting harness YES
connected to the vehicle
lighting harness at the grille?
NO
Connect both harnesses at
the grille?
Are snowplow headlamps
operating correctly?
NO
Run the snowplow and vehicle
lighting harness tests?
YES
YES
Is vehicle DRL system
functioning correctly?
NO
Correct the vehicle problem.
YES
For 1999-20_ GMC All New YES
Sierra and 1999-20_ Chevy
Silverado: Disconnect the
short plug-in harness from
the Isolation Module. Is 12
volts on position F of the 10pin connector?
For all other vehicles:
Refer to paragraph 1 above.
Using the Isolation
Module Tester, perform
Isolation Module Test.
NO
YES
Is the pink wire from the
plug-in harness
connected to the DRL
lamp positive feed wire?
NO
Connect the pink wire.
Lit. No. 27179
66
YES
Is there continuity
between position F of the
10-pin connector and the
pink DRL tap?
NO
Replace the short plug-in
harness.
July 2001
REMOVABLE SPRING TOOL
To Replace A Spring On The Blade, Follow The Instructions Below.
CAUTION
Servicing the trip springs
without special tools and
knowledge could result in
personal injury. See your
authorized FISHER® outlet for
service.
2. Place the assembly on to the top
anchor above the spring as
illustrated. Be sure to place the
spring bar in between the tabs on
the rod. Insert the 1/2 x 1-1/2" Gr.
5 cap screw through the outside
tab, through the hole in the spring
bar, and tighten into the threaded
hole.
3. Drop the 1/2" flat washer Gr. 8 over
the threaded rod and fasten the
nut to the threaded rod. Tighten
the nut until the spring bar is
raised enough to insert the pin
through the pin hole. Center the
pin within the hole.
4. Loosen the nut to lower the spring
bar. Remove the spring tool
assembly by removing the
1/2" cap screw.
1. Insert the threaded rod in through
the hole in the channel weldment.
Be sure the threaded hole in the
tab on the rod is nearest to the
channel.
5. Remove the spring from the blade
by removing the bolt from the
bottom of the spring bar.
1/2" Flat Washer Gr. 8
Channel
1/2 x 1-1/2"
Cap Screw Gr. 5
6. Insert the new spring with the
spring bar up through the top
anchor on the blade. Fasten the
bottom of the spring bar to the
anchor on the trip edge with the
previously removed fasteners.
Tighten.
1/2" Coupling
Nut
Rod
1/4 x 1-1/4" Pin
7. Repeat steps 1 and 2 above.
8. Repeat step 3 above, except
remove the pin from the spring bar.
9. Repeat step 4 above.
Lit. No. 27179
67
July 2001
NOTES
Lit. No. 27179
68
July 2001
Fisher Engineering
P.O. Box 529
Rockland, ME 04841
A DIVISION OF DOUGLAS DYNAMICS, L.L.C.
Copyright © 2001Douglas Dynamics. L.L.C. All rights reserved. This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film or other distribution and storage
media, without the written consent of Fisher Engineering. Authorization to photocopy items for internal or personal use by Fisher Engineering outlets is granted.
Fisher Engineering reserves the right under its product improvement policy to change construction or design details and furnish equipment when so altered without reference to illustrations or
specifications used herein. Fisher Engineering and the vehicle manufacturer may require and/or recommend optional equipment for snow removal. This product is manufactured under the following
patents: 4,280,062, 4,999,935, 5,353,530, 5,420,480, RE35700 and other patents pending. Fisher Engineering offers a limited warranty on all snowplows, spreaders and accessories. See separately
printed page for this important information. The following are registered® and unregistered™ trademarks of Douglas Dynamics, L.L.C.: EZ-V®, FISHER®, Fish-Stik®, Insta-Act®, Minute Mount®
Printed in USA
Lit. No. 27179
July 2001
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