For 1990-2009 cars

### Circuit Description

The torque converter (TCC) clutch solenoid is a pulse width modulated solenoid. When vehicle operating conditions are met for TCC application, the PCM begins the duty cycle at approximately 42%. The PCM 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.

### Conditions for Setting the DTC

DTC P0742 will set if TCC Release Pressure Switch is closed for 4 seconds, 4 times within an ignition cycle when:

• | Condition exist for longer than 6 seconds

• | Engine is running

• | TP Angle is greater than 8%

• | Trans. Fluid Temp. is between 21 and 130°C (68 and 266°F)

• | Gear ratio 3rd and 4th

• | TCC is commanded OFF

• | No engine torque default

• | Time since the last gear selector change is greater than 6 seconds

• | No TP Angle DTCs have set

• | Engine torque greater than 40 ft-lbs

P0742 is a type A DTC.

### Diagnostic Aids

Inspect and repair as necessary:

• | TCC 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.