Stop Lamp Switch
The task of the stop lamp switch is to provide the engine control module (ECM) with information about the position of the brake pedal.
When the brake pedal is depressed, a signal is sent to the engine control module (ECM) which switches off the cruise control (if it has been activated). Some versions have combined the stop lamp switch with the brake pedal sensor in one component. In other versions, these are two separate components fitted next to each other.
The stop lamp switch is supplied with power from the start control module (SCU) (terminal 30). When the brake pedal is depressed the switch closes and a high signal (12 V) is transmitted to the engine control module (ECM).
The engine control module (ECM) can diagnose the stop lamp switch. The status (position) of the switch can be read using the diagnostic tool.
The brake light switch is on the pedal box by the brake pedal.