P0740Powertrain
Powertrain · SAE
Torque Converter Clutch Circuit Malfunction
Meaning
The control module has detected a fault in the electrical or hydraulic circuit of the torque converter clutch (TCC). The TCC solenoid command signal is outside expected parameters.
Common causes
- Faulty TCC solenoid or open/short circuit in the control wiring
- Damaged, corroded, or broken TCC solenoid wiring or connectors
- Insufficient hydraulic pressure in the TCC circuit due to leaks or pump wear
- Clogged ATF filter or degraded transmission fluid
- Obstructed valve body with stuck TCC valve
- Internal transmission control module (TCM) fault
Symptoms
- Check engine light on
- Torque converter fails to lock or unlock during highway cruising
- Increased fuel consumption
- Transmission overheating
- Transmission entering limp mode
Severity
High: without torque converter lock-up, the transmission generates excessive heat, reducing fluid and transmission lifespan.
What to do
- Check ATF level and condition
- Measure TCC solenoid resistance and voltage with a multimeter
- Inspect TCC solenoid wiring and connectors
- Check hydraulic pressure at the TCC circuit with a gauge
- Replace TCC solenoid if outside specification