Circuit Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The normally-open stop lamp switch supplies battery voltage to the engine control module (ECM) when the brake pedal is pressed. The ECM sends a brake pedal applied serial data message to the electronic brake and traction control module (EBTCM) and to the transmission control module (TCM).