Action Taken By PCM
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
PCM performs the following if DTC is set:
- The PCM does not illuminate the MIL.
- The PCM enters PC solenoid valve diagnostic retest mode. The retest mode conducts the following diagnostic routine:
- The PCM de-energizes the PC solenoid valve, resulting in maximum line pressure.
- After being de-energized for 2 seconds, the PCM commands the PC solenoid valve on at .1 amp for the retest period of 5 seconds.
- If no circuit faults are detected during the 5-second retest period, then the PC solenoid valve is returned to normal operation and DTC P0748 diagnostic is passed. If a circuit fault is detected 3 times during normal operation, then the PCM de-energizes the PC solenoid valve for the remainder of that ignition cycle.
- If a circuit fault is detected during the 5-second retest period, then the PCM de-energizes the PC solenoid valve for 2 seconds before re-entering the retest mode. If a circuit fault is detected 5 times without returning to normal operation, then the PC solenoid valve is de-energized for the remainder of that ignition cycle.
- The PCM freezes shift adapts.
- The PCM records the operating conditions when the "Conditions for Setting the DTC" are met. The PCM stores this information as failure records.
- The PCM stores DTC P0748 in PCM history.