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 |
| • | TP Angle is greater than 8% |
| • | Trans. Fluid Temp. is between 21 and 130°C (68 and 266°F) |
| • | 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. |
