Brake-light/brake-test switches

Two switches are fitted on the brake pedal which supply the following signals:

S_BLS (brake-light switch)
S_BLTS (brake-light test switch)

The DME control unit evaluates the signals for the purpose of registering brake operation.

Function

Model series E38, E39, E46, E53, E6x, E8x:
The brake-light switch connects to earth (B-), the brake-light test switch connects to B+.
Model series E36/7 (Z3):
The brake-light switch and the brake-light test switch connect to B+.

Both signals are checked for plausibility.

The following tables show (depending on the model series) how the status of the brake-light switch/brake-light test switch performs:

Model series E38, E39, E46, E53, E6x, E8x	Brake pedal not operated	Brake pedal operated
Status, brake-light switch	Closed	Open
Status of brake-light test switch	Open	Closed

Model series E36/7 (Z3)	Brake pedal not operated	Brake pedal operated
Status, brake-light switch	Open	Closed
Status of brake-light test switch	Open	Closed

Troubleshooting

If the signals are not plausible in relation to one another, a fault code is stored in the DME control unit. Cruise control is deactivated as a result of this fault code memory entry.