Nissan Maxima Service and Repair Manual: P0744 torque converter

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 malfunctions (circuits open or shorted), but also by mechanical malfunctions such as control valve sticking, improper solenoid valve operation, etc.

DTC Logic

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

CAUTION: Always drive vehicle at a safe speed.

NOTE: Immediately after performing any "DTC CONFIRMATION PROCEDURE", always turn ignition switch OFF.

Then wait at least 10 seconds before performing the next test.

1.CHECK DTC DETECTION

With CONSULT

1.  Turn ignition switch ON.
2.  Select "Data Monitor" in "TRANSMISSION".
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)

With GST

Follow the procedure "With CONSULT".

Diagnosis Procedure

1.CHECK LINE PRESSURE

Perform line pressure test. Refer to TM-162, "Inspection and Judgment".

2.CHECK TORQUE CONVERTER CLUTCH SOLENOID VALVE

1.  Turn ignition switch OFF.
2.  Disconnect CVT unit connector.
3.  Check torque converter clutch solenoid valve. Refer to TM-70, "Component Inspection (Torque Converter Clutch Solenoid Valve)".

3.CHECK LOCK-UP SELECT SOLENOID VALVE

Check lock-up select solenoid valve. Refer to TM-70, "Component Inspection (Lock-up Select Solenoid Valve)".

4.CHECK SECONDARY SPEED SENSOR SYSTEM

Check secondary speed sensor system. Refer to TM-60, "DTC Logic".

5.CHECK PRIMARY SPEED SENSOR SYSTEM

Check primary speed sensor system. Refer to TM-57, "DTC Logic".

6.DETECT MALFUNCTIONING ITEMS

Check TCM connector pin terminals for damage or loose connection with harness connector.

Component Inspection (Torque Converter Clutch Solenoid Valve)

1.CHECK TORQUE CONVERTER CLUTCH SOLENOID VALVE

Check resistance between CVT unit connector terminal and ground.

Component Inspection (Lock-up Select Solenoid Valve)

1.CHECK LOCK-UP SELECT SOLENOID VALVE

Check resistance between CVT unit connector terminal and ground.