A/T TCC S/V Fnctn
DTC P0744 Improper Lock-Up OperationDESCRIPTION
- This is an OBD-II self-diagnostic item and not available in TCM self-diagnosis.
- This malfunction will not be detected while the O/D OFF indicator lamp is indicating another self-diagnosis malfunction.
- This malfunction is detected when the A/T does not shift into fourth gear position or the torque converter clutch does not lock up as instructed by the TCM. This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, malfunctioning oil pump or torque converter clutch, etc.
CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Remarks: Specification data are reference values.
TCM TERMINALS AND REFERENCE VALUE
Remarks: Specification data are reference values.
ON BOARD DIAGNOSIS LOGIC
This diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by TCM as follows:
Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from ECM
C: Gear ratio determined as gear position which TCM supposes.
If the actual gear position is much lower than the position (4th) supposed by TCM, the slip ratio will be much less than normal. In case the ratio does not reach the specified value, TCM judges this diagnosis malfunction.
This malfunction will be caused when shift solenoid valve B is stuck closed.
DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION PROCEDURE
CAUTION: Always drive vehicle at a safe speed.
NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
With CONSULT
1. Start engine and select "DATA MONITOR" mode for "A/T" with CONSULT.
2. Make sure that output voltage of A/T fluid temperature sensor is within the range below.
FLUID TEMP SEN: 0.4- 15V If out of range, drive the vehicle to decrease the voltage (warm up the fluid) or stop engine to increase the voltage (cool down the fluid).
3. Select "TCC S/V FNCTN P0744" of "DTC WORK SUPPORT" mode for "A/T" with CONSULT and touch "START".
4. Accelerate vehicle to more than 80 km/h (50 MPH) and maintain the following condition continuously until "TESTING" has turned to "COMPLETED". (It will take approximately 30 seconds after "TESTING" shows.)
THROTTLE POSI: 1/8 - 2/8 (at all times during step 4. Selector lever: D position (OD "ON")
TCC S/V DUTY: More than 94%
VHCL/S SE.A/T: Constant speed of more than 80 km/h (50 MPH)
- Check that "GEAR" shows "4".
- For shift schedule, refer to SDS.
- If "TESTING" does not appear on CONSULT for a long time, select "SELF-DIAG RESULTS". In case a 1st trip DTC other than P0744 is shown, refer to applicable "TROUBLE DIAGNOSIS FOR DTC".
5. Make sure that "OK" is displayed. (If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".)
Refer to "DIAGNOSTIC PROCEDURE". Refer to shift schedule.
With GST
1. Start engine and warm up ATF.
2. Start vehicle with selector lever in "D" (OD "ON") position and throttle opening 1/8 - 2/8. Check that vehicle runs through gear shift of D1 -> D2 -> D3 -> D4 -> D4 lock-up, in accordance with shift schedule. Refer to shift schedule.
3. Select "MODE 7" with GST.
No Tools
1. Start engine and warm up ATF.
2. Start vehicle with selector lever in "D" (OD "ON") position and throttle opening 1/8 - 2/8. Check that vehicle runs through gear shift of D1 -> D2 -> D3 -> D4 -> D4 lock-up, in accordance with shift schedule. Refer to shift schedule.
3. Perform self-diagnosis for ECM.
Steps 1 - 3:
Steps 4 - 8:
Steps 9 - 15:
Diagnostic Procedure
WIRING DIAGRAM
Component Inspection
Solenoid Valves
Resistance Check
- Check resistance between terminals (3, 2, 4, 6 or 7. and ground.
Operation Check
- Check solenoid valve by listening for its operating sound while applying battery voltage to the terminals (3, 2, 4, 6 or 7. and ground.