Shift Interlock: Description and Operation

Key Interlock


Battery voltage is supplied at all times through fuse 39 to the key interlock switch. When the key is in the ignition, battery voltage is supplied to the key interlock solenoid and the key interlock circuit in the interlock control unit. If the A/T gear position switch is in any position but PARK, battery voltage is applied to the base of the transistor. With the transistor on, the solenoid is energized and the key cannot be removed from the ignition. When the A/T gear position switch is in PARK, the base of the transistor is grounded at G501. With the transistor off, the solenoid is not energized and the key can be removed from the ignition.


Shift Position Interlock


Battery voltage is supplied at all times through fuse 39 to the brake switch. With the ignition in RUN or START, battery voltage is supplied from fuse 13 to the shift lock solenoid. When you push the brake pedal, battery voltage is applied through the GRN/WHT wire to the powertrain control module (PCM). If the accelerator pedal is NOT pushed, a low voltage signal is then sent through the RED/BLU wire to the powertrain control module(PCM). So, with the brake pedal pushed and the accelerator released, the powertrain control module (PCM) shift lock relay control output will apply voltage through the BLU/BLK wire to the shift lock relay in the interlock control unit. If the shift position console switch is in the PARK position, the relay will be energized and the contacts will close. The shift lock solenoid will then be energized and the shift lever can be moved from the PARK position.