P0744

P0744 Torque Converter

Description

This malfunction is detected when the A/T does not lock-up. 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.

SDT Reference Value in Data List Mode






On Board Diagnosis Logic

- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "P0744" with SDT or 3rd judgment flicker without SDT 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 SDT

1 Start engine.
2 Select "Data list" mode for "AT" with SDT.
3 Drive vehicle and maintain the following conditions for at least 30 consecutive seconds.
ACCELE POSI: More than 1.0/8
SLCT LVR POSI: "D" position
TCC SOLENOID: 0.4 - 0.6 A
VEHICLE SPEED: 80 km/h (50 MPH) or more
Driving locations: Driving the vehicle uphill (increased engine load) will help maintain the driving conditions required for this test.
4 If DTC is detected, go to "Diagnosis Procedure".

with GST

Follow the procedure "WITH SDT".

Diagnosis Procedure

1. CHECK INPUT SIGNAL

With SDT
1 Turn ignition switch ON.
2 Select "MAIN SIGNALS" in "Data list" mode for "AT" with SDT.
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. Refer to [Main Power Supply and Ground Circuit Check] Main Power Supply and Ground Circuit Check.

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. Refer to [Control Valve with TCM: Removal and Installation] Service and Repair.
NG
Repair or replace damaged parts.

4. CHECK DTC

Perform "DTC Confirmation Procedure".
- Refer to "DTC Confirmation Procedure".

OK or NG
OK
INSPECTION END
NG
GO TO 2.