P0742

P0742 - TCC SYSTEM STUCK ON (L61)





The Torque Converter (TCC) clutch solenoid is a pulse width modulated solenoid. When vehicle operating conditions are met for TCC application, the PCM/TCM begins the duty cycle at approximately 42%. The PCM/TCM then increases the duty cycle up to 90% in order to achieve full TCC apply. When the TCC solenoid is de-energized, the solenoid blocks filtered 2-3 drive fluid, and allows TCC signal fluid to exhaust. When energized, the solenoid modulates fluid into the TCC signal fluid circuit. When fully energized, modulation stops, and the solenoid blocks both 2-3 drive fluid and TCC signal fluid exhaust.
The TCC release switch is a normally closed switch. It signals the PCM the TCC is released. Torque converter release fluid pressure acts on the switch contact, opening the circuit. When the voltage on the circuit is high, the PCM recognizes the TCC is no longer engaged.

DTC PARAMETERS
DTC P0742 will set if TCC release pressure is equal to No for 16 seconds when:
- Engine speed is between 500 and 6500 RPM.
- TP angle is greater than 12%.
- TFT is between 21°C (70°F) and 130°C (266°F).
- Engine torque is between 27 and 407 Nm (20 and 300 ft. lbs.).
- TCC is commanded OFF.
- Time since last manual range change greater than 6 seconds.
- No TCC release switch or TP sensor DTCs have been set.
- Vehicle speed is between 32 and 97 km/h (20 and 60 mph).
- Transmission range is equal to Drive 4.

P0721 is a type A DTC.

DIAGNOSTIC AIDS
Inspect and repair as necessary:
- TTC solenoid exhaust restricted.
- TCC solenoid filter plugged.
- TCC control valve stuck in the released position.
- TCC regulated apply valve stuck in the released position.
- TCC feed limit valve stuck.
- Pressure regulator valve stuck.
- TCC fluid circuit leaks.
- TCC release switch for damaged or leaking seal, debris in switch, damaged switch contacts, stuck switch contacts.