Automatic Transmission Shift Lock System

The automatic transmission shift lock control is a safety device that prevents an inadvertent shift out of PARK when the ignition is ON. 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 automatic transmission shift lock control switch.
• The park/neutral safety switch.

With the ignition in the ON position, battery positive voltage is supplied to the automatic transmission shift lock control switch. The circuit continues through the normally-closed switch to the automatic transmission shift lock control solenoid. The park/neutral safety switch provides a path to ground for the automatic transmission shift lock control solenoid in the PARK position. This energizes the automatic transmission shift lock control solenoid, mechanically locking the shift linkage in the PARK position. When the driver presses the brake pedal the contacts in the automatic transmission shift lock control switch open, causing the automatic transmission shift lock control solenoid to de-energize. This allows the shift lever to move from the PARK position. When the shift lever is out of the PARK position the contacts in the neutral safety switch open and the automatic transmission shift lock control solenoid is de-energized.