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 (brake) lamp switch
The stop (brake) lamp switch is a single pole switch positioned at the brake pedal lever. It self-adjusts during its installation.
The stop (brake) lamp switch transmits signals informing the control module that braking has started. The control module interrupts any traction control and goes to standby mode for ABS / EBD control, which means that the control module can make more accurate calculations. If the control module does not receive a signal from the stop (brake) lamp switch, there is still ABS control available but the control is more vigorous at the start of the ABS control.
The stop (brake) lamp switch is supplied with power from the battery. When the switch closes, the stop (brake) lamp lights and the control module receives a signal that braking is occurring.
In All-wheel drive (AWD) cars equipped with TRACS, the stop (brake) lamp switch has two switches to ensure that traction control stops when braking. If a fault occurs in the stop lamp switch signal the traction control in the TRACS function is reduced from operating on all the wheels to operating on the front wheels only.
There are diagnostics for the stop (brake) lamp switch.
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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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