Description & Operation: Introduction

The automatic transmission (A/T) shift lock control system 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 A/T shift lock control solenoid. Also referred to as brake transmission shift interlock (BTSI) solenoid.
• The A/T shift lock control switch (stoplamp switch).
• The park relay.
• The rear integration module (RIM).
• The automatic transmission internal mode switch.
• The powertrain control module (PCM).

With the ignition in the ON position, battery voltage is supplied to the park relay coil. When the RIM energizes the park relay, the park relay switch contacts close suppling voltage to the A/T shift lock control switch. The circuit continues through the normally closed switch to the A/T shift lock control solenoid. The permanently grounded solenoid is energized. This locks the shift linkage in the PARK position. When the driver presses the brake pedal, the contacts in the A/T shift lock control switch open. This causes the A/T shift lock control solenoid to release, which allows the shift lever to move from the PARK position.