Toyota A750F automatic transmission Repair manual

AT–82
A750F AUTOMATIC TRANSMISSION – AUTOMATIC TRANSMISSION SYSTEM
DTC
P0751
Shift Solenoid "A" Performance (Shift Solenoid
Valve S1)
DESCRIPTION
The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual
gear position (1st, 2nd, 3rd, 4th or 5th gear).
Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical
problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).
DTC No.
DTC Detection Conditions
Trouble Areas
1
P0751
S1 stuck ON malfunction* :
The ECM determines that there is a malfunction when
the following conditions are met (2-trip detection logic):
(a) When the ECM directs the gearshift to switch to 4th
gear, the actual gear is shifted to 1st.
(b) When the ECM directs the gearshift to switch to 1st
gear, the actual gear is also shifted to 1st.
•
•
•
•
Shift solenoid valve S1 remains open
Shift solenoid valve SLT remains open or closed
Valve body is blocked
Automatic transmission (clutch, brake or gear, etc.)
S1 stuck OFF malfunction*2:
The ECM determines that there is a malfunction when
the following conditions are met (2-trip detection logic):
(a) When the ECM directs the gearshift to switch to 1st
gear, the actual gear is shifted to 4th.
(b) When the ECM directs the gearshift to switch to 5th
gear, the actual gear is also shifted to 5th.
•
•
•
•
Shift solenoid valve S1 remains closed
Shift solenoid valve SLT remains open or closed
Valve body is blocked
Automatic transmission (clutch, brake or gear, etc.)
HINT:
Gear positions in the event of a solenoid valve mechanical problem:
Gearshift controlled by ECM
1st
2nd
3rd
4th
5th
*1: Actual gear position under S1 stuck ON malfunction
1st
2nd
2nd
1st
N*
*2: Actual gear position under S1 stuck OFF malfunction
4th
3rd
3rd
4th
5th
N*: Neutral
MONITOR DESCRIPTION
AT
This DTC indicates "stuck ON malfunction" or "stuck OFF malfunction" of the shift solenoid valve S1. The
ECM controls the gearshifts by turning the shift solenoid valves "ON/OFF". When the gear position
directed by the ECM and the actual gear position do not match, the ECM illuminates the MIL and stores
the DTC.
MONITOR STRATEGY
Related DTCs
P0751:
Shift solenoid valve S1/OFF malfunction
Shift solenoid valve S1/ON malfunction
Required sensors/Components (Main)
Shift solenoid valve S1
Required sensors/Components (Related)
Vehicle speed sensor, Throttle position sensor, Speed sensor (NT),
Speed sensor (SP2)
Frequency of operation
Continuous
Duration
OFF malfunctions (A) and (B):
0.4 seconds
OFF malfunction (C):
Immediate
ON malfunctions (A), (B) and (C):
0.4 seconds
ON malfunction (D):
3 seconds
ON malfunction (E):
0.5 seconds
MIL operation
2 driving cycles
A750F AUTOMATIC TRANSMISSION – AUTOMATIC TRANSMISSION SYSTEM
Sequence of operation
AT–83
None
TYPICAL ENABLING CONDITIONS
The following conditions are common to all OFF malfunctions (A), (B) and (C) and ON malfunctions (A),
(B), (C), (D) and (E).
The monitor will run whenever the following DTCs are not present.
P0115 - P0118: ECT sensor
P0125: Insufficient ECT for Closed Loop
P0500: VSS
P0748 - P0799: Trans solenoid (range)
Turbine speed sensor (NT) circuit
No circuit malfunction
Output speed sensor (SP2) circuit
No circuit malfunction
Shift solenoid "A" (S1) circuit
No circuit malfunction
Shift solenoid "B" (S2) circuit
No circuit malfunction
Shift solenoid "E" (SR) circuit
No circuit malfunction
Pressure control solenoid "A" (SL1) circuit
No circuit malfunction
Pressure control solenoid "B" (SL2) circuit
No circuit malfunction
ECT (Engine Coolant Temperature) sensor circuit
No circuit malfunction
Knock sensor circuit
No circuit malfunction
ETCS (Electronic Throttle Control System)
System not down
Transmission shift position
"D"
ECT
40°C (104°F) or more
Spark advance from max. retard timing by knock sensor control
0° CA or more
Engine
Starting
Transfer range
"High" *1
*1: Following conditions are met
Vehicle speed sensor "A" circuit
No circuit malfunction
Output speed sensor circuit
No circuit malfunction
Transfer output speed
143 rpm or more
Transfer input speed/Transfer output speed
0.9 to 1.1
OFF malfunction (A)
ECM selected gear
1st
Vehicle speed
1.2 to 24.9 mph (2 to 40 km/h)
Throttle valve opening angle
8 % or more
and
6.5 % or more at engine speed of 2,000 rpm
(Conditions vary with engine speed)
OFF malfunction (B)
Current ECM selected gear
5th
Last ECM selected gear
4th
Continuous time of ECM selecting 4th gear
2 seconds or more
Actual gear when ECM selected 4th gear
4th
OFF malfunction (C)
Current ECM selected gear
5th
Last ECM selected gear
4th
ON malfunction (A)
ECM selected gear
1st
Vehicle speed
1.2 to 24.9 mph (2 to 40 km/h)
Throttle valve opening angle
6.5 % or more at engine speed of 2,000 rpm
(Conditions vary with engine speed)
AT
AT–84
A750F AUTOMATIC TRANSMISSION – AUTOMATIC TRANSMISSION SYSTEM
ON malfunction (B)
ECM selected gear
4th
Vehicle speed
1.2 mph (2 km/h) or more
Throttle valve opening angle
6.5 % or more at engine speed of 2,000 rpm
(Conditions vary with engine speed)
ON malfunction (C)
ECM selected gear
3rd
Vehicle speed
1.2 mph (2 km/h) or more
Throttle valve opening angle
6.5 % or more at engine speed of 2,000 rpm
(Conditions vary with engine speed)
ON malfunction (D)
Current ECM selected gear
5th
Last ECM selected gear
4th
Vehicle speed
(During transition from 4th to 5th gear)
Less than 62.2 mph (100 km/h)
ON malfunction (E)
ECM selected gear
5th
Engine speed - Turbine speed (NE - NT)
(After transition from 4th to 5th gear)
150 rpm or less
Vehicle speed
(After transition from 4th to 5th gear)
Less than 62.2 mph (100 km/h)
TYPICAL MALFUNCTION THRESHOLDS
[OFF malfunction]
All of the following conditions are met: OFF malfunctions (A), (B) and (C)
2 detections are necessary in 1 driving cycle.
1st detection; temporary flag ON
2nd detection; pending fault code ON
OFF malfunction (A)
Turbine speed/Output speed
AT
0.93 to 1.07
(Actual gear is 4th)
OFF malfunction (B)
Turbine speed/Output speed
0.65 to 0.79
(Actual gear is 5th)
OFF malfunction (C)
Output record from ECM for 4th → 5th upshifting
Recorded
[ON malfunction]
Either of the following conditions is met:
• ON malfunctions (A) and (B)
• ON malfunction (B) or (C) and ON malfunction (D) or (E)
ON malfunction (A)
Turbine speed/Output speed
3.30 to 7.50
(Actual gear is 1st)
ON malfunction (B)
Turbine speed/Output speed
3.30 to 7.50
(Actual gear is 1st)
ON malfunction (C)
Turbine speed/Output speed
1.91 to 2.35
(Actual gear is 2nd)
A750F AUTOMATIC TRANSMISSION – AUTOMATIC TRANSMISSION SYSTEM
AT–85
ON malfunction (D)
Turbine speed - Output speed x 4th gear ratio
1,000 rpm or more
ON malfunction (E)
Turbine speed - Output speed x 5th gear ratio
1,000 rpm or more
INSPECTION PROCEDURE
HINT:
Performing the ACTIVE TEST using the intelligent tester allows components, such as the relay, VSV, and
actuator, to be operated without removing any parts. Performing the ACTIVE TEST as a first step of
troubleshooting is one method of shortening labor time.
It is possible to display the DATA LIST during the ACTIVE TEST.
1. Warm up the engine.
2. Turn the ignition switch off.
3. Connect the intelligent tester together with the CAN VIM (Controller Area Network Vehicle Interface
Module) to the DLC3.
4. Turn the ignition switch to the ON position.
5. Push the "ON" button of the tester.
6. Clear the DTC.
7. Select the items "DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / SHIFT".
8. According to the display on the tester, perform the "ACTIVE TEST".
HINT:
While driving, the shift position can be changed with the intelligent tester.
Comparing the shift position directed by the ACTIVE TEST with the actual shift position enables the
problem to be confirmed (See page AT-35).
Item
Test Details
Diagnostic Note
SHIFT
[Test Details]
Operate the shift solenoid valve and set each
shift position manually.
[Vehicle Condition]
Vehicle Speed: Less than 30 mph (50 km/h)
[Others]
• Press → button: Shift up
• Press ← button: Shift down
Possible to check the operation of the shift
solenoid valves.
HINT:
Shifting to the 5th gear is possible only when
the vehicle is stationary with the engine idling.
HINT:
• This test can be conducted when the vehicle speed is 30 mph (50 km/h) or less.
• The 4th to 5th up-shifting must be performed with the accelerator pedal released.
• The 5th to 4th down-shifting must be performed with the accelerator pedal released.
• Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
• The shift position directed by the ECM is shown in the DATA LIST / SHIFT display on the intelligent
tester.
• The shift solenoid valve S1 is turned on/off normally when the shift lever is in the D position:
1
Gearshift controlled by ECM
1st
2nd
3rd
4th
5th
Shift solenoid valve S1
ON
ON
OFF
OFF
OFF
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0751)
(a) Connect the the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and push the
intelligent tester main switch ON.
(c) Select the items "DIAGNOSIS / ENHANCED OBD II /
DTC INFO / CURRENT CODES".
AT
AT–86
A750F AUTOMATIC TRANSMISSION – AUTOMATIC TRANSMISSION SYSTEM
(d) Read the DTCs using the intelligent tester.
Result:
Display (DTC Output)
Proceed to
Only "P0751" is output
A
"P0751" and other DTCs
B
HINT:
If any codes besides "P0751" are output, perform
troubleshooting for those DTCs first.
B
GO TO DTC CHART
A
2
PERFORM ACTIVE TEST USING INTELLIGENT TESTER (SOLENOID (SLT))
SST
SST
AT
G020657E01
NOTICE:
• Perform the test at the normal operating ATF
(Automatic Transmission Fluid) temperature: 50 to
80°C (122 to 176°F).
• Be careful to prevent SST's hose from interfering with
the exhaust pipe.
• Perform the test with the A/C OFF.
HINT:
Performing the intelligent tester's ACTIVE TEST allows relay,
VSV, actuator and other items to be operated without
removing any parts. Performing the ACTIVE TEST early in
troubleshooting is one way to save time.
The DATA LIST can be displayed during the ACTIVE TEST.
(a) Remove the test plug on the transmission case center
right side and connect SST.
SST 09992-00095 (09992-00231, 09992-00271)
(b) Connect the intelligent tester to the DLC3.
(c) Start the engine and warm it up.
(d) Measure the line pressure with SST.
(e) Turn the intelligent tester ON.
(f) Enter the following menus: DIAGNOSIS / ENHANCED
OBD II / ACTIVE TEST.
(g) Follow the instructions on the tester and perform the
ACTIVE TEST.
(h) Measure the line pressure with SST.
Item
Test Details
Diagnostic Note
SOLENOID (SLT)*
[Test Details]
Operate shift solenoid SLT and raise line pressure.
[Vehicle Condition]
• Vehicle stopped
• IDL: ON
HINT:
OFF: Line pressure up (when Active Test of
"SOLENOID (SLT)" is performed, ECM commands SLT
solenoid to turn off)
ON: No action (normal operation)
-
A750F AUTOMATIC TRANSMISSION – AUTOMATIC TRANSMISSION SYSTEM
AT–87
*: "SOLENOID (SLT)" in the ACTIVE TEST is performed
to check the line pressure changes by connecting SST to
the automatic transmission, which is used in the
HYDRAULIC TEST (See page AT-18) as well. Please
note that the pressure values in the ACTIVE TEST and
HYDRAULIC TEST are different.
NG
REPLACE SHIFT SOLENOID VALVE SLT
OK
3
INSPECT SHIFT SOLENOID VALVE S1
(a) Remove the shift solenoid valve S1.
(b) Measure the resistance.
Standard resistance
Shift Solenoid Valve S1:
Tester Connection
Specified Condition
Solenoid Connector (S1) - Solenoid
Body (S1)
11 to 15 Ω at 20°C (68°F)
(c) Connect the positive (+) lead to the terminal of the
solenoid connector, and the negative (-) lead to the
solenoid body.
OK:
The solenoid makes operating sounds.
(-)
(+)
NG
REPLACE SHIFT SOLENOID VALVE S1
A110986E04
OK
4
INSPECT TRANSMISSION VALVE BODY ASSEMBLY (See chapter 2 in the problem
symptoms table)
OK:
There are no foreign objects on any valves and they
operate smoothly.
NG
REPAIR OR REPLACE TRANSMISSION
VALVE BODY ASSEMBLY
OK
REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY
AT