Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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 control solenoid.
- Shift lock control switch (part of stoplamp switch).
- Park/Neutral Position (PNP) switch.
With the ignition switch in the ON position, battery voltage is supplied to the stoplamp switch. The circuit continues through the normally closed switch to the shift lock control solenoid. The PNP switch provides a path to ground in the Park position. With the shift lock control solenoid energized, the gearshift lever is mechanically locked in the Park position. When the driver presses the brake pedal, the contacts in the stoplamp switch open, de-energizing the shift lock control solenoid. This allows the gearshift lever to move from the Park position.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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