Circuit/System Description
WARNING: This page is about a different car, the 2006 Buick Lucerne. However, it is still accessible from the selected car via links, so may be relevant.
When the brake pedal is applied, the BCM receives a brake applied signal from the brake pedal position sensor (BPPS). The BCM applies B+ to the stop lamp switch signal circuit. This circuit supplies a B+ signal to the powertrain control module (PCM) (L26), engine control module (ECM) (LD8), transmission control module (TCM) (LD8) and the throttle actuator control (TAC) module (L26).