P0744

DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)





Description
- This malfunction is detected when the torque converter clutch does not lock-up as instructed by the TCM.
This is not only caused by electrical malfunction (circuits open or shorted), but also by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.




CONSULT-III Reference Value









On Board Diagnosis Logic
- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "P0744 A/T TCC S/V FNCTN" with CONSULT-III is detected under the following conditions.
- When CVT cannot perform lock-up even if electrical circuit is good.
- When TCM compares difference value with slip revolution and detects an irregularity.




Possible Cause
- Torque converter clutch solenoid valve
- Hydraulic control circuit




DTC Confirmation Procedure

CAUTION:
Always drive vehicle at a safe speed.

NOTE:
If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch OFF and wait at least 10 seconds before performing the next test.
After the repair, touch "ERASE" on "SELF-DIAG RESULTS" and then perform the following procedure to confirm the malfunction is eliminated.

WITH CONSULT-III
1. Turn ignition switch ON.
2. Select "DATA MONITOR" mode for "TRANSMISSION" with CONSULT-III.
3. Start engine and maintain the following condition for at least 30 seconds.
ACC PEDAL OPEN: More than 1.0/8
RANGE: "D" position
Vehicle speed: Constant speed of more than 40 km/h (25 MPH)
4. If DTC is detected go to "Diagnosis Procedure".

WITH GST
Follow the procedure "WITH CONSULT-III".




Diagnosis Procedure
1.CHECK INPUT SIGNALS
With CONSULT-III
1. Start engine.
2. Select "ECU INPUT SIGNALS" in "DATA MONITOR" mode for "TRANSMISSION" with CONSULT-III.
3. Start vehicle.
4. Check if there is a great difference between "ENG SPEED SIG" and "PRI SPEED SEN". (Lock-up ON.)





OK or NG
OK >> GO TO 5.
NG >> GO TO 2.
2.CHECK LINE PRESSURE
Perform line pressure test. Refer to Inspections Before Trouble Diagnosis.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts. Refer to Inspections Before Trouble Diagnosis.
3.DETECT MALFUNCTIONING ITEM
Check the following:
- Torque converter clutch solenoid valve. Refer to P0740.
- Lock-up select solenoid valve. Refer to P1740.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
4.CHECK OUTPUT SPEED SENSOR (SECONDARY SPEED SENSOR) SYSTEM AND INPUT SPEED
SENSOR (PRIMARY SPEED SENSOR) SYSTEM
Check output speed sensor (secondary speed sensor) system and input speed sensor (primary speed sensor) system. Refer to P0720, P0715.
OK or NG
OK >> GO TO 5.
NG >> Repair or replace damaged parts.
5.CHECK DTC
Perform "DTC Confirmation Procedure".
OK or NG
OK >> INSPECTION END
NG >> GO TO 6.
6.CHECK TCM
1. Check TCM input/output signals. Refer to TCM Input/Output Signal Reference Value.
2. If NG, re-check TCM pin terminals for damage or loose connection with harness connector.
OK or NG
OK >> INSPECTION END
NG >> 1. Repair or replace damaged parts.
2. Replace the transaxle assembly. Refer to .