Circuit Chart:
Circuit assignments for the Body Control Module (BCM) relating to gearshift:
GEARSHIFT UNLOCK
The gearshift unlock solenoid is energized by the BCM switching circuit 1135 to ground. When energized, the gearshift unlock solenoid will allow shifting from PARK. A condition for shifting from PARK is that the foot brake must be applied. The BCM receives this information over the serial data link from the engine controller.
The BCM also monitors ignition 1 circuit 39 and accessory circuit 43 to determine if the ignition switch is in the RUN or ACC position.