[35B] Four-Wheel Anti-Skid Brake System (4ABS)

[35B] Four-Wheel Anti-Skid Brake System (4ABS)
35B-1
GROUP 35B
CONTENTS
GENERAL INFORMATION . . . . . . . .
CONSTRUCTION DESCRIPTION . . .
35B-2
35B-6
SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . .
35B-6
ABS-ECU. . . . . . . . . . . . . . . . . . . . . . . . . . .
35B-6
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
35B-2
GENERAL INFORMATION
GENERAL INFORMATION
M2351000100379
FEATURES
EBD CONTROL
The ABS ensures directional stability and controllability during hard braking.
For vehicles with this type of ABS, 4 sensors (4
channels) are installed on front and rear wheels
allowing independent left and right control.
The system has the following features:
NOTE: On vehicles with active stability control system, the ABS system is controlled by the ABS/active
stability control system-ECU. For the system construction, refer to GROUP 35C, General Information
P.35C-2.
• EBD (Electronic Brake-force Distribution system)
control has been added to provide the ideal braking force for the rear wheels.
• Magnetic encoder for wheel speed detection has
been installed as a sensing device instead of the
rotor.
• For wiring harness saving and secure data communication, CAN* bus has been adopted as a
tool of communication with another ECU.
NOTE: *: For more information about CAN (Controller Area Network), refer to Group 54CP.54C-2.
In ABS, electronic control is used so the rear wheel
brake hydraulic pressure during braking is regulated
by rear wheel control solenoid valves in accordance
with the vehicle's rate of deceleration, and the front
and rear wheel slippage which are calculated from
the signals received from the various ABS sensors.
EBD control is a control system which provides a
high level of control for both vehicle braking force
and vehicle stability. The system has the following
features:
• Because the system provides the optimum rear
wheel braking force regardless of vehicle load
conditions and the condition of the road surface,
the system reduces the required pedal depression force, particularly when the vehicle is heavily
loaded or driven on road surfaces with high frictional coefficients.
• Because the duty placed on the front brakes is
reduced, the increases in pad temperature can
be controlled during brakes application to
improve the wear resistance characteristics of the
pad.
• Control valves such as the proportioning valve
are not required.
SPECIFICATIONS
Item
Specification
ABS control method
4-sensor, 4-channel
Wheel speed
sensor
Magnetic encoder
Type
Front
86 (N pole:43 S pole:43)
Rear
86 (N pole:43 S pole:43)
Semiconductor
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
35B-3
GENERAL INFORMATION
CONSTRUCTION DIAGRAM
4
5
AC311642
3, 7
6
1
2
AC311643
1
AC311644AB
Name of part
Number
Outline of function
Sensor
Wheel speed sensor
1
Sends alternating current signals at frequencies which are
proportional to the rotation speeds of each wheel to the
ABS-ECU.
Stop lamp switch
2
Sends a signal to the ABS-ECU to indicate whether the
brake pedal is depressed or not.
3
Drives the solenoid valves according to signals from the
ABS-ECU in order to control the brake hydraulic pressure
for each wheel.
ABS warning lamp
4
Illuminates in response to signals from the ABS-ECU
when a problem develops in the system.
Brake warning lamp
5
Illuminates in response to signals from the ABS-ECU
when a problem develops in the EBD system.
6
Outputs the diagnosis codes and allows communication
with the MUT-III.
Actuator Hydraulic unit
Diagnosis connector
35B-4
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
GENERAL INFORMATION
Name of part
Number
Outline of function
ABS-ECU
7
Controls actuators (described above) based on the signals
coming from each sensor.
Controls the self-diagnosis and fail-safe functions.
Controls the diagnostic function (MUT-III compatible).
SYSTEM CONFIGURATION DIAGRAM
Engine-ECU <M/T> or Engine-A-M/T-ECU*
<Automated manual transmission>
Front right solenoid valve (out)
Front-left wheel speed sensor
Rear-left wheel speed sensor
Rear-right wheel speed sensor
Front right solenoid valve (in)
Front left solenoid valve (out)
Front-right wheel speed sensor
Brake fluid level switch
Front left solenoid valve (in)
Rear right solenoid valve (out)
Stop lamp switch (two systems)
ABS-ECU
Parking lever switch
Rear right solenoid valve (in)
Rear left solenoid valve (out)
Rear left solenoid valve (in)
ABS-ECU power supply
Brake warning lamp
ABS warning lamp
Diagnosis connector
Stop lamp switch (two systems)
Brake fluid
level switch
Front-right wheel (FR)
Rear-right wheel (RR)
Front-right
wheel
speed
sensor
Rear-right wheel
speed sensor
Hydraulic
unit (HU)
Parking lever switch
Front-left wheel
speed sensor
Front-left wheel (FL)
NOTE: Broken lines show CAN-bus line.
Rear-left wheel
speed sensor
Rear-left wheel (RL)
AC314135AB
NOTE: Engine-A-M/T-ECU*: Engine Automated
Manual Transmission Electronic Control Unit
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
35B-5
GENERAL INFORMATION
ABS ELECTRICAL CIRCUIT DIAGRAM
Fusible
link No.1
Ignition
switch (IG1)
Fusible
link No.5
Fusible
link No.3
Fusible
link No.6
J/B
(Fuse)
No.40
7.5A
No.42
15A
J/B
(Fuse)
No.33
15A
Stop lamp
switch
On On
Off
Off
Hydraulic unit (HU)
Electric
power
steering
Solenoid valve
Motor
Stop lamp
ABS-ECU
Motor power
supply
Front
wheel
speed
sensor (LH)
Off
Brake fluid
On level switch
Front
wheel
speed
sensor (RH)
Solenoid valve
power supply
Rear
wheel
speed
sensor (LH)
Rear
wheel
speed
sensor (RH)
Parking
Off
brake
switch
Motor power
supply
Engine-ECU <M/T> or
Engine-A-M/T-ECU
<Automated manual
transmission>
J/C
(CAN2)
On
J/C
(CAN1)
Diagnosis connector
Combination meter
(ABS warning lamp and
brake warning lamp)
AC314136 AC
35B-6
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
CONSTRUCTION DESCRIPTION
CONSTRUCTION DESCRIPTION
SENSORS
M2351001000234
WHEEL SPEED SENSORS AND MAGNETIC ENCODER FOR WHEEL SPEED
DETECTION
Rear
Front
Encoder for wheel
speed detection
Encoder for wheel
speed detection
AC311647
AC311648
Rear ABS sensor
Front ABS sensor
AC312272AB
Wheel speed sensor is a kind of a pulse generator
consisted of a magnetic encoder (a plate on which
north and south pole sides of the magnets are
arranged alternately) for wheel speed detection
which rotates at the same speed of the wheels and a
speed sensor (semiconductor sensor), and it outputs
frequency pulse signals in proportion to wheel
speed.
Front wheel speed sensor consists of a front wheel
speed sensor secured on the knuckle, and a magnetic encoder for wheel speed detection fitted to the
inside of the front wheel bearing. Rear wheel speed
sensor consists of a rear wheel speed sensor
secured on the rear hub, and a magnetic encoder for
wheel speed detection press fitted to the rear hub
inner ring.
ABS-ECU
M2351003000218
• By integrating ABS-ECU into the hydraulic unit,
no more wiring harnesses for sending signal that
operates the solenoid valve and pump motor is
required, assuring higher reliability.
• Self-diagnostic programs and memory functions
are integrated into ABS-ECU. If any malfunction
is detected by the self-diagnostic function,
ABS-ECU activates a fail-safe function and illuminates ABS warning lamp and brake warning
lamp*.
NOTE: *: ABS-ECU illuminates the brake warning
lamp as EBD control warning lamp.
• ABS-ECU detects vehicle speed from the wheel
speed sensor signal, recognizes the wheel rotation, estimates the wheel slip condition based on
the preprogrammed algorithm, and then controls
the solenoid valve in the hydraulic unit so that the
wheels do not lock.
ABS FLUID PRESSURE CONTROL
ABS CONTROL CYCLE
The hydraulic unit is basically the same as that of the
2000 PAJERO PININ.
FOUR-WHEEL CONTROL
4-wheel independent control
Vehicle travelling
Independent
direction
control
Independent
control
Independent
control
Independent
control
AC208547AC
ABS fluid pressure is controlled independently for
four wheels.
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
CONSTRUCTION DESCRIPTION
35B-7
EBD FLUID PRESSURE CONTROL
EBD operating conceptual design
Braking force distribution
by EBD control
Ideal distribution curve when
seated by fixed persons
Rear braking force
Braking force distribution curve
by the existing proportioning valve
Ideal distribution curve when seated by one persons
Braking Force
Improved
Front braking force
AC208548AB
EBD control is activated within the lower slip ratio
area where ABS is disabled. EBD calculates vehicle
deceleration and slip amount of the four wheels
based on the wheel speed sensor signal. If the rear
wheel speed differs from the vehicle speed by a certain level or more, EBD boost, holds, and depressurises the rear wheel control solenoid valve in the
hydraulic unit, and then adjusts rear wheel brake
fluid pressure fairly close to an ideal distribution
curve.
INITIAL CHECK
ABS-ECU internally activates the self-diagnostic
function. ABS-ECU illuminates ABS warning lamp for
3 seconds (including the initial check) * after the ignition switch is turned ON. If any malfunction is
detected, ABS-ECU continues illuminating ABS
warning lamp and disables ABS control.
NOTE: *: ABS warning lamp may stay ON after the
ignition switch is turned ON until the startup vehicle
speed reaches approximately 10km/h. As far as
ABS-ECU memorizes any diagnosis code related to
the wheel speed sensor malfunction recorded during
previous ignition ON status, ABS-ECU continues illuminating ABS warning lamp until it verifies that the
malfunction for that code is resolved (Startup check).
STARTUP CHECK
When the startup vehicle speed reaches approximately 15km/h, ABS-ECU performs the following
checks.
1. Motor, solenoid valve check (only in initial
startup*)
Operates the motor relay in ECU and checks the
pump motor operation. At the same time,
ABS-ECU sequentially energizes each solenoid
valve in a very short period and checks the valve
operation.
NOTE: *: Initial startup indicates a first startup
after the system has started.
2. Wheel speed sensor check
ABS-ECU checks for any wheels that have not
received ABS sensor signal from the startup.
CONSTANT CHECK
ABS-ECU constantly checks the following items.
1. ABS-ECU
Performs self-diagnosis in ECU.
2. ECU power supply
Checks if ECU power supply voltage reaches
within the operational range.
3. Wheel speed sensor
(1) Monitors the output voltage of the sensor
signal wiring harness and checks for abnormal
output voltage (open/short circuit).
(2) Checks for any wheels that do not send pulse
signal while the vehicle is in motion.
(3) Checks if wheel speed which is abnormally
higher or lower than the vehicle speed is input.
4. Pump motor and solenoid valve
Checks that ABS-ECU output signal and the
operating condition of the pump motor and
solenoid valve agree with each other.
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
35B-8
CONSTRUCTION DESCRIPTION
CAN COMMUNICATION
FAIL - SAFE FUNCTION
ABS-ECU outputs ABS warning lamp and EBD
warning lamp* illumination request signals to the
combination meter through CAN communication.
NOTE: *: ABS-ECU illuminates the brake warning
lamp as EBD control warning lamp.
If any malfunction is detected by the self-diagnostic
function, ABS-ECU illuminates ABS warning lamp
and brake warning lamp*, and it controls ABS and
EBD as shown in the following table.
NOTE: *: ABS-ECU illuminates the brake warning
lamp as EBD control warning lamp.
Diagnosis
code No.
Item
C1200
Open or short
circuit in wheel
speed sensor (FR)
C1201
C1205
C1206
C1210
C1211
C1215
C1216
C1225
Action during fail-safe operation
ABS control
EBD control CAN output Brake
warning
lamp
ABS
warning
lamp
ABS disabled
• Prohibited
Two or less Output
wheel
permitted
abnormal
• Enabled
Two or less
wheel
Abnormal:
OFF
Three or
more
wheels
Abnormal:
ON
ON
Open or short
ABS disabled
circuit in wheel
• Prohibited
speed sensor (RR)
ABS enabled
Wheel speed
• Depressurise
sensor (RR)
s rear wheel
system
brake fluid
pressure.
Open or short
Prohibits all
circuit in wheel
wheel
speed sensor (RL)
control after
Wheel speed
control is
sensor (RL) system
completed.
Two or less Output
wheel
permitted
abnormal
• Enabled
Two or less
wheel
Abnormal:
OFF
Three or
more
wheels
Abnormal:
ON
ON
Wheel speed
System
sensor malfunction shut-down
System
shut-down
ON
ON
ABS enabled
Wheel speed
• Prohibits
sensor (FR) system
Three or
control of
more
malfunctioni
Open or short
wheels
ng
wheel.
circuit in wheel
abnormal
Prohibits
all
speed sensor (FL)
• Prohibited
wheel
Wheel speed
control after
sensor (FL) system
control is
completed.
Three or
more
wheels
abnormal
• Prohibited
Output
permitted
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
35B-9
CONSTRUCTION DESCRIPTION
Diagnosis
code No.
Item
Action during fail-safe operation
C1226
Control solenoid
Prohibited
valve (FR) pressure
holding system
C1231
Control solenoid
valve (FR)
decompressing
system
C1236
Control solenoid
valve (FL) pressure
holding system
C1241
Control solenoid
valve (FL) pressure
reducing system
C1246
Control solenoid
valve (RR)
pressure holding
system
C1251
Control solenoid
valve (RR)
pressure reducing
system
C1256
Control solenoid
valve (RL) pressure
holding system
C1261
Control solenoid
valve (RL)
decompressing
system
C1266
Motor system
(stuck)
C1273
Motor relay stuck
off
C1274
Motor relay stuck
on
C1276
ABS control
EBD control CAN output Brake
warning
lamp
ABS
warning
lamp
Prohibited
Output
permitted
ON
ON
Prohibited
Enabled
Back up
mode
Output
permitted
ON
ON
Valve relay system
System
shut-down
System
shut-down
Output
permitted
ON
ON
C1278
Valve relay system
stuck off
System
shut-down
Control
disabled
Output
permitted
ON
ON
C1279
Valve relay system
stuck on
Control
disabled
Control
enabled on
valve relay
system
Output
permitted
OFF
ON
C1345
Brake fluid level
failure
Enabled
Enabled
Output
permitted
ON
OFF
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
35B-10
CONSTRUCTION DESCRIPTION
Diagnosis
code No.
Item
C1398
C1607
Action during fail-safe operation
EBD control CAN output Brake
warning
lamp
ABS
warning
lamp
Gas Test is running Prohibited
Prohibited
Output
permitted
ON
ON
Trouble in
ABS-ECU
Prohibited
Prohibited
Output
permitted
ON
ON
Trouble in
ABS-ECU (CAN
Initialization
malfunction)
Enabled
Enabled
Output
impossible
ON *1
ON *1
C1860
High voltage at
ABS-ECU power
supply (16.8V or
more)
Wait
Wait
Output
permitted
ON
ON
C1861*2
Low voltage at
Wait
ABS-ECU power
supply (9.6V or
less, 7.6V or more)
Enabled
Output
permitted
OFF
ON
Low voltage at
ABS-ECU power
supply (7.6V or
more)
Wait
Output
permitted
ON
ON
Enabled
Output
prohibited
ON *1
ON *1
U1073
ABS control
Wait
Trouble in CAN bus Enabled
system
NOTE: .
• *1: If any trouble occurs in CAN communication,
the brake warning lamp and ABS warning lamp
on the combination meter turns ON.
*2
• : DTCs are recorded only when the vehicle
speed is 6km/h or more.
• Prohibit: Any controls are not performed until the
ignition switch is turned OFF.
• Wait: ABS control is restarted when the normal
condition is resumed even though the ignition
switch is not turned OFF.
DIAGNOSTIC FUNCTION
• Actuator test
DIAGNOSIS CODE SET
There are 22 diagnostic items. Since all the diagnostic results are recorded in volatile memory (EEPROM*), they are stored in the memory even though
the battery terminals are disconnected.
NOTE: .
• *EEPROM (Electrical Erasable &;Programmable
ROM): Special type of memory that can be programmed or erased electrically
• For each diagnostic item, refer to Fail-safe Function.
SERVICE DATA OUTPUT
ABS-ECU has the following functions for easier system checks. The following items can be diagnosed
The following items of the ECU input data can be
using the MUT-III.
read using MUT-III.
• Diagnosis code set
The system is normal
• Service data output
Item No.
Check items
Check conditions
Normal conditions
01
FR wheel speed sensor
02
FL wheel speed sensor
03
RR wheel speed sensor
04
RL wheel speed sensor
Perform a test run of the vehicle. Speedometer display and
MUT-III display almost agree
with each other.
FOUR-WHEEL ANTI-SKID BRAKE SYSTEM (4ABS)
35B-11
CONSTRUCTION DESCRIPTION
Item No.
Check items
Check conditions
Normal conditions
05
Power supply voltage
Always
10 V or more
06
Stop lamp switch
The brake pedal is depressed
ON
The brake pedal is released.
OFF
ACTUATOR TEST
Activation Pattern
End of
activation
Start of
activation
Solenoid A
valve
B
C
0.05 s
On
Pump
motor Off
1s
2s
0.01 s
Note
A: Hydraulic pressure increases
B: Hydraulic pressure holds
C: Hydraulic pressure decreases
NOTE: .
• When ABS-ECU is disabled, the actuator test
cannot be performed.
• The actuator test can be performed only when
the vehicle is stationary. When the vehicle speed
reaches 10km/h, the forcible actuator operation is
disabled.
• During actuator test, the ABS warning lamp illuminates, and ABS control is prohibited.
• Refer to Service Manual for actuator test specification.
• ABS warning lamp continues illuminating until the
communication between MUT-III and ABS-ECU
is completed.
Item No. Check item
Drive Contents
01
Solenoid valve for
front-right wheel
02
Solenoid valve for
front-left wheel
03
Solenoid valve for
rear-right wheel
Solenoid valves
and pump motor in
the hydraulic unit
(simple inspection
mode)
04
Solenoid valve for
rear-left wheel
AC300188AB
The MUT-III can be used to force-drive all solenoid
valves and the pump motor.
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