Circuit/System Description

The stop lamp switch signal circuit is a voltage input from the body control module (BCM) to the engine control module (ECM). The ECM monitors the stop lamp switch circuit to detect when the brake pedal has been applied. The BCM monitors the brake pedal position sensor to determine when the brake pedal is applied. When the brake pedal is applied, the BCM supplies a voltage signal on the brake applied signal circuit and also sends a serial data message to the ECM indicating that the brake pedal has been applied.