Brake light switch

Together with the signal from the brake pressure sensor, braking operations are detected. Two Hall effect sensors as switches are installed in the brake light switch: the brake light switch and the brake light test switch (redundancy for safety reasons). The signals indicate whether the brake pedal has been pressed. The data interchange is digital.

Fig 1: Identifying Brake Light Switch And Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

The two redundant signals from the brake light switch are read in by the Car Access System (CAS). The CAS forwards the signals on the bus system, e.g. for the engine control system.

The signals from the brake light switch are hard-wired and branched off for the following systems:

• Dynamic Stability Control (DSC) for the brake intervention
• Footwell module (FRM) for reversing light