P0743

DTC P0743 Torque Converter Clutch Circuit Electrical:

Torque Converter Clutch:

CIRCUIT DESCRIPTION

The Torque Converter Clutch (TCC) Solenoid is used to engage the lock-up clutch. The Transmission Control Module (TCM) outputs system voltage to turn ON (energize) or remove voltage to turn OFF (de-energize) to control the hydraulic pressure to the lock-up valve within the transmission. The TCC solenoid is always OFF in 1st and 2nd gears. The TCC is ON in 3rd and 4th gears when the TCM deems it appropriate. The TCC solenoid is NEVER on during 4L operation or when the engine coolant temperature is below 30°C (8O°F).


FAILURE CONDITION

Voltage detected at terminal "12" is 2.0 V or lower when TCC control solenoid valve is "ON" or 5.5 V or higher when it is "OFF"


ACTION TAKEN

A DTC P0743 is stored, TCM enters fail-safe mode and both the "OD/OFF" and "SERVICE ENGINE SOON" indicators are turned "ON."

DTC CHART TEST DESCRIPTION

Numbers below refer to the circled numbers on the diagnostic chart.

1. Checks for proper resistance values.

2. Checks for a short to ground in GRN/YEL wire.

3. Checks for an open in GRN/YEL wire.

4. Checks for a short to voltage in GRN/YEL wire.

5. Checks for a poor electrical connection that may have caused DTC to set.

6. Checks for a defective TCM.


DIAGNOSTIC AIDS

Check for poor connections at component and inline harness connector terminal connections before replacing components. After repairs have been made, repeat the TCM OBD System Check to ensure system is functioning normally.