Description & Operation: Introduction

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 gearshift lever out of the Park position. The system consists of the following components:

• Shift lock solenoid and park lock solenoid (part of floor shift control assembly).
• Stoplamp switch.

With the ignition switch in the ON position, voltage is supplied to stoplamp switch. Voltage flows through the normally closed contacts of the stoplamp switch to the shift lock solenoid. The shift lock solenoid is permanently grounded. This energizes the shift lock solenoid causing the gearshift lever to be physically locked in the Park position. When the brake pedal is pressed, the contacts in the stoplamp switch open, de-energizing the shift lock solenoid. This allows the gearshift lever to be moved from the Park position.