The PARK/REV fuse in the underhood fuse block supplies battery positive voltage through CKT 1940 (ORN) to the PARK relay at terminal A1. The CRUISE fuse in the underhood fuse block supplies ignition voltage through CKT 339 (PNK) to the PARK relay at terminal A3. The body control module (PZM) receives the park/neutral position switch status from the powertrain control module (PCM) via the Class 2 serial data line CKT 1807 (PPL). When the PZM determines that the vehicle is in PARK, the PZM energizes the PARK relay by grounding CKT 434 (ORN/BLK). Once the PARK relay is energized, battery voltage is supplied through CKT 275 (LT GRN) to the stoplamp/BTSI switch connector C2 terminal A . When the brake pedal is in the rest position (not pressed), battery voltage is supplied from the stoplamp/BTSI switch terminal B through CKT 1135 (DK GRN/WHT) to the shift interlock actuator terminal A . The actuator is grounded by one of the following circuits:

The actuator remains energized as long as the brake pedal is at rest (not pressed). This condition locks the gear shift lever in the PARK position. Pressing the brake pedal opens the stoplamp/BTSI switch. This action removes the battery voltage from the shift interlock actuator. The actuator de-energizes, unlocking the gear shift lever. When the PZM determines that the vehicle is not in the PARK position, the PZM de-energizes the PARK relay by removing the ground from CKT 434 (ORN/BLK). This action disables the BTSI system until the driver moves the gear shift lever back to PARK.