P0744

DTC P0744 A/T TCC S/V 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.

CONSULT-II 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-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.

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, perform the following procedure to confirm the malfunction is eliminated.

With CONSULT-II





1. Start engine and Select TCC S/V FNCTN CHECK of DTC WORK SUPPORT mode for A/T with CONSULT-II and touch START.
2. 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)]
- Make sure GEAR shows 5.
- For shift schedule, refer to AT-63, Vehicle Speed at Which Lock-up Occurs/Releases. Shift Schedule
- 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.
3. Make sure that OK is displayed. (If NG is displayed, refer to DIAGNOSTIC PROCEDURE.) Refer to AT-127, Diagnostic Procedure. Refer to shift schedule AT-63, Vehicle Speed at Which Lock-up Occurs/Releases. Shift Schedule

WITH GST
Follow the procedure WITH CONSULT-II.

Diagnostic Procedure
1. CHECK INPUT SIGNAL

With CONSULT-II





1. Turn ignition switch ON.
2. Select MAIN SIGNALS in DATA MONITOR mode for A/T with CONSULT-II.
3. Start the engine.
4. Read out the value of TCC SOLENOID while driving.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.

2. CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.

3. DETECT MALFUNCTIONING ITEM
Check the following.
- The A/T assembly harness connector pin terminals for damage or loose connection with harness connector.
OK or NG
OK >> Replace the control valve with TCM.
NG >> Repair or replace damaged parts.

4. CHECK DTC
Perform DTC Confirmation Procedure.
- Refer to AT-126, DTC Confirmation Procedure.
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.