Circuit Description
WARNING: This page is about a different car, the 2004 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
The stop lamp switch signal circuit is a direct hardwire input to the engine control module (ECM) from the electronic brake control module (EBCM). The ECM monitors the stop lamp switch signal circuit in order to detect when the brake pedal has been applied. When the brake pedal is pressed, the EBCM sends a class 2 serial data message to the ECM indicating that the brake pedal has been applied. The EBCM also sends a high voltage signal on the stop lamp switch signal circuit to the ECM. This DTC will set if the class 2 serial data message and the voltage signal on the stop lamp switch signal circuit do not match.