Circuit Operation

SHIFT INTERLOCK
When the Ignition Switch is in the ON position or when retained accessory power is active, the shift interlock system prevents the driver from shifting the vehicle from park unless the brake pedal is depressed. Pressing the brake pedal de-energizes the solenoid. The restrictor arm moves clear of the shift lever arm, allowing the gear selector to operate normally.

To override the shift interlock system and shift the vehicle, turn the ignition switch to OFF. This removes battery voltage at the solenoid, leaving the solenoid de-energized.

BRAKE-TO-SHIFT INDICATOR (BUICK ONLY)
On Buick only, the park/neutral position switch also contains a transaxle range switch. This component is a multi-signal switch which sends information relative to gear selector position to the Powertrain Control Module (PCM) via four discrete circuits. The PCM in turn, sends a signal over the UART data line to the instrument cluster. If the instrument cluster receives a Park signal from the PCM, it turns on the BRAKE-TO-SHIFT indicator. If it receives any other signal, the indicator does not light.

IMPORTANT:
On vehicles equipped with Retained Accessory Power (RAP), open any door to remove battery voltage at the solenoid.