Automatic Transmission Shift Lock Control System

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. The system consists of the following components:

• The automatic transmission shift lock control solenoid
• The body control module (BCM)
• The transmission control module (TCM)
• The stop lamp switch
• The shift lock release button

The stop lamp switch controls the voltage supply circuit of the shift lock control solenoid. The following conditions must be met before voltage is supplied to the shift lock control solenoid:

• The ignition is in the ON position.
• The stop lamp switch turns ON when the brake pedal is applied.
• The shift lock release button is pressed.

With the above conditions met, the stop lamp switch supplies voltage to the shift lock control solenoid. When the brake pedal is depressed the stop lamp switch turns ON and the BCM sends a message via CAN communication to the TCM indicating the brakes are applied. With the stop lamp switch ON, voltage is supplied to the shift lock control solenoid. This energizes the shift lock control solenoid releasing the mechanical lock, allowing the driver to move the shift lever out of the PARK position.