The brake light switch informs the DSC3 control unit as to when the brake pedal is operated.
During ASC control, brake intervention is terminated immediately, the intake valve closed and the changeover valve opened.
The ABS control procedure is also terminated immediately if during ABS controlled braking the brake is released thus opening the brake light switch.
In the case of the DSC3 the entire system (ABS, ASC and DSC) is switched off if the brake light switch is defective.