Circuit/System Description

WARNING: This page is about a different car, the 2008 Saturn Sky and 2008 Pontiac Solstice. However, it is still accessible from the selected car via links, so may be relevant.

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