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.
Stop Lamp Switch
The task of the stop lamp switch is to provide the Engine Control Module (ECM) with information about the position of the brake pedal.
When the brake pedal is pressed down, a signal is sent to the Engine Control Module (ECM) which turns off the cruise control (if it is activated). The brake pedal switch position (connected to the brake control module (BCM)) also handles the function for switching off the cruise control.
For further information, see DESIGN AND FUNCTION, BRAKE CONTROL MODULE (BCM) .
The stop lamp switch is supplied with power from the start control module (SCU) (terminal 30). When the brake pedal is depressed the switch closes and a high signal (12 V) is transmitted to the Engine Control Module (ECM).
The Engine Control Module (ECM) can diagnose the stop lamp switch. The status (position) of the switch can be read using the diagnostic tool.
The brake light switch is on the pedal box by the brake pedal.
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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.