Subject: | Engine Surge or Stall at Stop and Or DTC P0742 Possible TCC Applied |
Models: | 2001-2007 Chevrolet Silverado Classic |
2007-2008 Chevrolet Silverado |
2001-2008 GMC Sierra Classic |
2007-2008 GMC Sierra |
Equipped With Allison LCT1000 Transmission RPO M74 or MW7 |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Customer may comment that the vehicle will surge or stall when in gear at a stop. Technicians may find DTC P0742 or feel the TCC is applied.
To help isolate if the concern is transmission internal or external use the following diagnosis.
If the vehicle still stalls and the concern can be isolated to the transmission check cooler flow (SI document 1633903), inspect the TCC pwm solenoid and valve in the main valve body. Also inspect the TCC valve and TCC relief valve in the pump cover.
If the vehicle does not stall inspect wiring between the TCM and transmission if no concern is found swap TCM from a known good vehicle.
Note: The above information is meant only as a diagnostic aid and WILL NOT isolate an engine driveability related concern.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.