P0742Powertrain
Powertrain · SAE
Torque Converter Clutch Stuck On
Meaning
The torque converter clutch (TCC) remains locked in the engaged (closed) position even when the control module has not requested activation. The torque converter cannot perform its shock-absorbing function at low speeds.
Common causes
- TCC solenoid mechanically stuck in the open position, maintaining clutch engagement via residual hydraulic pressure
- TCC valve in the valve body stuck in the closed position
- Excessive hydraulic pressure in the TCC circuit due to blockage of the exhaust circuit
- Worn TCC clutch with friction material bonded to the drum
- Short circuit to ground in TCC wiring keeping the solenoid permanently energized
Symptoms
- Check engine light on
- Engine stall or shutdown at very low speeds or during braking
- Vibration or shudder when releasing the brake
- Transmission does not disengage at low speeds
- Difficulty maneuvering at low speed
Severity
High: a stuck-on TCC prevents normal torque converter operation and can cause engine stall and mechanical damage to the converter.
What to do
- Check ATF level and condition
- Use a scan tool to verify whether the TCC solenoid is actually commanded off when the problem occurs
- Measure TCC solenoid resistance and check for wiring short circuits
- Inspect the valve body for a stuck TCC valve
- Replace the TCC solenoid or overhaul the torque converter if necessary