Shift Interlock: Description and Operation

Gear Shift Interlock:

A gear shift interlock system is introduced for 1993 model year. The system prevents movement of the gear selector from PARK unless the ignition switch is in position II and the brake pedal is applied. In addition, the ignition key cannot be removed from the ignition switch unless the gear selector is in PARK. Once the key is removed, the selector is locked in PARK.

System operation
The system is controlled through the CPU (central microprocessor) with inputs for brake pedal applied, PARK position and ignition key in position II. The brake pedal applied input is sourced from the brake switch; the PARK position input is sourced from the PARK micro switch on the J gate assembly and the ignition switch position II input is sourced from the ignition power supply circuit.

The CPU energizes the gear shift solenoid in response to the input signals that the brakes are applied and the ignition is in position II. The energized solenoid moves the locking mechanism allowing the gear selector to be moved out of PARK. When the gear selector is moved out of PARK the CPU energizes the key lock solenoid to prevent ignition key removal. The CPU de-energizes the key lock solenoid in response to the input signal that the gear selector is in PARK thus allowing ignition key removal.

Interlock Mechanism:

Key Lock:

System components

The system components are as follows:
^ Central microprocessor located under the passenger's side dash panel
^ Gear shift solenoid and key lock solenoid relays [2) in relay module M located under the passenger's side front seat
^ Gear shift solenoid and locking mechanism located on the J gate assembly
^ PARK micro switch located on the J gate assembly
^ Key lock solenoid located on the steering column

Manual Override Release:

Manual override
If the vehicle must be moved without power, the gearshift locking mechanism can be disengaged. To prevent inadvertent use, the release requires a two-handed operation. Depress the button at the top of the J gate with an implement such as the ignition key and move the lever out of PARK. An audible warning sounds for 10 seconds if the ignition key is not in position II when the gear selector is moved from PARK.