Circuit/System Description
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) provides a 10-volt reference voltage and a low reference signal to the brake pedal position sensor (BPPS). When the brake pedal is applied, the BPPS sends a variable voltage signal through the brake apply sensor signal circuit to the BCM. The voltage signal will increase as the brake pedal is further depressed. In response to this signal, the BCM applies battery positive voltage to the stop lamp switch signal circuit and the rear stop/turn lamp supply voltage circuits.