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 (redundant for safety reasons). The signals indicate whether the brake pedal has been pressed. The data transfer is digital.

The Car Access System (CAS) supplies the brakelamp switch with power from Terminal R.

Fig 1: Identifying Brake Light Switch And 4-Pin Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

The engine control receives both brakelamp-switch signals. One of the two signals is transferred to the DSC through a hard-wired secondary connection. After a plausibility check in the engine control unit, the signal is transmitted to the DSC on the PT-CAN.