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
The stop lamps are in the tail lamps. The lamps light when the stop lamp switch on the brake pedal is closed. The stop lamp switch is connected to the central electronic module (CEM). The signal from the stop lamp switch is sent on to the rear electronic module (REM) via a hardwired cable. The power supply for the lamps is via a directly connected relay in the rear electronic module (REM). In order for the stop lamps to work when the ignition is not on, there is no logic in the rear electronic module (REM) to activate the relay. The relay is activated directly by the signal from the stop lamp switch. The rear electronic module (REM) receives data via the controller area network (CAN) from the central electronic module (CEM) indicating that the stop lamp switch is activated.
To detect faults in the stop lamps, the rear electronic module (REM) reads the power consumption of the lamp circuit. If the power consumption falls below a certain limit, a fault is indicated and a text message is displayed in the driver information module.
There are diagnostics for the stop lamps.
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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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