P0744

DTC P0744 A/T TCC SN FUNCTION (LOCK-UP)
Description
This malfunction is detected when the A/T does not shift into 5th gear position or 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.

On Board Diagnosis Logic
^ This is an OBD-II self-diagnostic item.
^ Diagnostic trouble code "A/T TCC SN FNCTN" with CONSULT-II or P0744 without CONSULT-II is detected under the following conditions.
- When A/T cannot perform lock-up even if electrical circuit is good.
- When TCM detects as irregular by comparing difference value with slip rotation.

Possible Cause
^ Harness or connectors
(The solenoid circuit is open or shorted.)
^ Torque converter clutch solenoid valve
^ Hydraulic control circuit

DTC Confirmation Procedure

CAUTION: Always drive vehicle at a safe speed.

e1mNOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.

After the repair. Perform the following procedure to confirm the malfunction is eliminated.

WITH CONSULT-II





1. Start engine and select "DATA MONITOR" mode for "A/T" with CONSULT-II.
2. Select "TCC SN FNCTN CHECK" of "DTC WORK SUPPORT" mode for "A/T" with CONSULT-II and touch "START".
3. Accelerate vehicle to more than 80 km/h (50 MPH) and maintain the following condition continuously until "TESTING" has turned to "COMPLETE". (It will take approximately 30 seconds after "TESTING" shows.)
ACCELE POSI: More than 1.0/8 (at all times during step 4)
TCC SOLENOID: 0.4 - 0.6 A
Selector lever: "D" position
[Reference speed: Constant speed of more than 80 km/h (50 MPH)]
- Check that "GEAR" shows "5".
- For shift schedule, refer to "Vehicle Speed When Performing and Releasing Complete Lock-up".
- If "TESTING" does not appear on CONSULT-II 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".
4. Make sure that "OK" is displayed. (If "NO" is displayed, refer to "DIAGNOSTIC PROCEDURE".)
Refer to "Diagnostic Procedure".
Refer to shift schedule, "Vehicle Speed When Performing and Releasing Complete Lock-up".

WITH GST
Follow the procedure "With CONSULT-II".








Wiring Diagram-AT-TCCSIG

Diagnostic Procedure
1. CHECK TORQUE CONVERTER CLUTCH SOLENOID VALVE CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect A/T unit assembly harness connector at the transmission right side.








3. Check the resistance between terminal and ground.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.

2. CHECK TERMINAL CORD ASSEMBLY
1. Remove oil pan. Refer to "Control Valve Assembly".
2. Disconnect A/T unit assembly harness connector and control valve assembly harness connector.








3. Check continuity between A/T unit assembly harness connector and control valve assembly harness connector.
4. If OK, check harness for short to ground and short to power.
5. Reinstall any part removed.
OK or NG
OK >> GO TO 3.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.

3. CHECK VALVE RESISTANCE
Check valve resistance
^ Refer to "Component Inspection".
OK or NG
OK >>GO TO 5.
NG >>Replace the control valve assembly.

4. CHECK POWER SOURCE CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect TCM connector.








3. Check continuity between A/T unit assembly harness connector and TCM connector.
4. If OK, check harness for short to ground and short to power.
5. Reinstall any part removed.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.

5. CHECK DTC
Perform "DTC Confirmation Procedure".
OK or NG
OK >> INSPECTION END
NG >> GO TO 6.

6. PERFORM TCM INSPECTION
1. Perform TCM input/output signal inspection. Refer to "TCM Input/Output Signal Reference Values"
2. If NG, recheck TCM pin terminals for damage or loose connection with harness connector.
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.

Component Inspection
TORQUE CONVERTER CLUTCH SOLENOID VALVE
Resistance Check
1. Turn ignition switch OFF.
2. Remove oil pan. Refer to "Control Valve Assembly".
3. Disconnect control valve assembly harness connector.








4. Check resistance between terminal and ground.
5. If NO, replace control valve assembly.

Operation Check





^ Check solenoid valve by listening for its operating sound while applying battery voltage to the terminal 11 and ground.