P0742

WITH 4L60-E AUTOMATIC TRANSMISSION

DTC P0742 Torque Converter Clutch (TCC) Stuck "On" Diagnostic Chart:

Torque Converter Clutch (TCC):

CIRCUIT DESCRIPTION
The Vehicle Control Module-A (VCM-A) energizes the Torque Converter Clutch (TCC) solenoid by creating a ground path on CKT 422. When grounded (Energized) by the VCM-A the TCC enable solenoid stops converter signal oil from exhausting. This causes converter signal oil pressure to increase and shift the TCC valve. The TCC solenoid will de-energize when the VCM-A no longer provides a ground. When the TCC solenoid is de-energized it will exhaust fluid and release the TCC. DTC Type (D).

DTC P0742 WILL SET WHEN
- No DTC(s) P0122, P0123, or P1810 are set.
- TCC slip speed RPM indicates between -20 and +20.
- TCC solenoid is commanded "OFF."
- TP sensor signal is greater than 25%.
- Trans range switch indicates D2, D3 or D4.
- Commanded gear indicates 3rd or 4th gear.
- Engine speed is greater than 300 RPM.
- All conditions are met for 4 seconds.

ACTION TAKEN (VCM-A will default to)
The VCM-A will turn "ON" the Malfunction Indicator Lamp (MIL) (if applicable), and DTC P0742 will be stored in VCM-A memory.

DTC P0742 WILL CLEAR DEFAULT ACTION WHEN
Fault condition no longer exists and the ignition switch is cycled "OFF" for five seconds, then "ON".

DTC P0742 WILL PASS WHEN
VCM-A slip speed is equal to or less than -20 RPM: or is equal to or greater than +20 RPM when:
- Drive 2, 3, or 4 is selected.
- Throttle Position Sensor (TPS) is greater than 25%
- All enable criteria are met.
- The VCM-A turns "OFF' the Malfunction Indicator Lamp (MIL) after three consecutive ignition cycles with reported passes (if applicable).

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks the mechanical state of the TCC.
When the VCM-A commands the TCC solenoid "OFF", TCC slip speed should increase.

DIAGNOSTIC AIDS
If the TCC is mechanically stuck "ON", vehicle speed is greater than 7 MPH, brakes are applied, and D2 is selected, the TCC fluid will mechanically apply the TCC causing an engine stall.
Scan Throttle Position (TP) signal while depressing accelerator pedal with engine "OFF" and ignition "ON". Display should vary from below 0.85 volts when the throttle is closed to over 4.0 volts when the throttle is held at wide open throttle. Incorrect TP sensor values may affect TCC operation.