Circuit/System Description
WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) applies a ground through the brake pedal position sensor (BPPS) low reference circuit to the BPPS. The BCM supplies a 5-volt reference through the brake sensor reference voltage circuit to the BPPS.
When the brake pedal is being applied, the BPPS then sends a variable voltage through the brake sensor signal circuit to the BCM.