Theory Of Operation

WARNING: This page is about a different variant/trim than selected.

The purpose of the diagnostic is to monitor if the hard-wired High Side Control circuit state is equal to the ignition signal state received on the Controller Area Network (CAN) Bus. The High Side Control is sent by the Powertrain Control Module (PCM) to the transmission. This circuit is used to supply power to the Park Lock Solenoid.

This transmission requires hydraulic pressure to overcome spring pressure to disengage the Park Pawl. If hydraulic pressure is lost, the Park Pawl will engage placing the transmission in Park. The Park Lock Solenoid, when energized after the transmission is hydraulically taken out of Park, holds the transmission out of Park until the solenoid is commanded Off. This can allow the vehicle to maintain mobility in the event the Transmission Control Module (TCM) cuts power to the solenoids for Limp-in mode. Since the solenoid is powered by the Powertrain Control Module (PCM), the vehicle may need to be shut off to engage Park.