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.
Brake light switch
Two Hall effect sensors as switches are installed in the brake light switch:
- Brake lamp switch
- Brake light test switch (redundancy).
The signals indicate whether the brake pedal has been pressed. The data interchange is digital.
The brake-light switch has no moving parts and works as a non-contact switch. A change in the switching state is achieved by removing or applying a ferromagnetic trigger element to the brake pedal.
Switching mode with brake not applied:
- Brake light switch output conductive
- Brake light test switch output blocking.
| Index | Explanation |
|---|---|
| 1 | Brake light switch |
| 2 | 4-pin plug connection |
| 3 | Brake pedal pressed |
| 4 | Brake pedal not pressed |
The two redundant signals from the brake light switch are forwarded for example to the Digital Engine Electronics (DME).
The signals from the brake light switch are also evaluated for the following functions:
- Reversing lamps
- Brake intervention.
NO RELATED
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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.