Shift Interlock: Description and Operation

Automatic Transmission Shift Lock Control Description and Operation
The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the PARK position.

Column Shift
The column shift system consists of the following components:
^ The park relay
^ The automatic transmission shift lock solenoid
^ The automatic transmission shift lock control switch
^ The rear integration module (RIM)
^ The powertrain control module (PCM)
With the ignition ON, positive voltage is supplied from the ignition switch to the coil side feed circuit of the park relay. The RIM receives a gear position input signal from the PCM through a class 2 serial data message. When the RIM receives a PARK position message from the PCM, the RIM applies a ground to the control circuit of the park relay. This energizes the relay, closing the switch contracts in the relay. Battery voltage flows through the relay to the automatic transmission shift lock control switch. With the brake pedal released, voltage flows through the normally closed contacts of the automatic transmission shift lock control switch to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is permanently grounded. This energizes the automatic transmission shift lock control solenoid, mechanically locking the shift lever in the PARK position. When the driver presses the brake pedal, the contacts of the automatic transmission shift lock control switch open, de-energizing the automatic transmission shift lock control solenoid. This allows the shift lever to be moved out of the PARK position.
When the shift lever is moved out of the PARK position, the PCM sends a class 2 serial data message to the RIM. The RIM then opens the ground path of the park relay control circuit, de-energizing the park relay and disabling the automatic transmission shift lock control solenoid. Once the vehicle is out of PARK, the automatic transmission shift lock control solenoid remains de-energized until the RIM receives a PARK signal from the PCM.

Console Shift
The console shift system consists of the following components:
^ The park relay
^ The ignition 3 relay
^ The automatic transmission shift lock control switch
^ The automatic transmission shift lock control solenoid
^ The automatic transmission shift lock control relay
^ The rear integration module (RIM)
^ The powertrain control module (PCM)
With the ignition ON, battery voltage is supplied to the coil side feed circuit of the brake to shift relay. When the RIM receives a PARK signal though a class 2 serial data message from the PCM the RIM grounds the control circuit of the brake to shift relay. This energizes the brake to shift relay coil and closes the switch contacts in the relay. Battery voltages flows through the switch side of the park relay to the automatic transmission shift lock control switch. The contacts in the automatic transmission shift lock control switch are normally closed allowing voltage to flow to the coil side of the shift lock relay. The coil side of the shift lock relay is permanently grounded. This energizes the shift lock relay, opening the normally closed switch side contacts. With the switch contacts open the automatic transmission shift lock control solenoid de-energizes, locking the shift lever in the PARK position. When the driver presses the brake pedal the contacts in the automatic transmission shift lock control switch open, de-energizing the shift lock relay. The switch side contacts close and voltage form the ignition 3 relay flows through the shift lock relay contacts to the permanently ground automatic transmission shift lock control solenoid. The solenoid energizes and unlocks the shift lever, allowing the driver to move the shift lever out of the PARK position.
When the shift lever is moved out of the PARK position, the PCM sends a class 2 serial data message to the RIM. The RIM then opens the ground path of the park relay control circuit, de-energizing the park relay and the shift lock relay. Once the vehicle is out of PARK, the automatic transmission shift lock control solenoid remains energized or unlocked until the RIM receives a PARK signal from the PCM.

Shift Lock Bypass Procedure
In the event that service is required, a park lock solenoid manual release lever is located on the right side of the floor shift assembly. To operate the manual release, block the wheels and apply the parking brake. Remove the shift lever trim panel and depress the release lever, move the shift lever to the NEUTRAL position while the lever is depressed.

Reverse Lockout System Description and Operation
Reverse Lockout Control (Console Shift Only)
The reverse lockout system is a safety device that prevents an inadvertent shift from a forward or neutral gear into reverse. The system consists of the following components:
^ The reverse lockout relay
^ The reverse lockout solenoid
^ The dash integration module (DIM)
When the ignition switch is turned ON, battery voltage is supplied to the coil side feed circuit of the reverse lockout relay. The DIM supplies the ground for the control side circuit. When the DIM determines that the ignition is ON and the vehicle has been traveling at over 8 km (5 mph) for 15 seconds or longer, it grounds the control circuit of the reverse lockout relay. This energizes the relay and the switch side contacts close. Battery voltage flows through the switch side contacts of the relay to the reverse lockout solenoid. The reverse lockout solenoid is permanently grounded, this energizes the reverse lockout solenoid and mechanically prevents the shift lever from being moved into the REVERSE position.