Circuit/System Description

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5 V reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will send a serial data message to the Lighting Control Module, the Lighting Control Module responds by applying battery voltage to the stop lamps/center high mount stop lamp control circuit illuminating the left and right stop lamps and the center high mounted stop lamp. If serial data communication is lost between the BCM and the Lighting Control Module, the Lighting Control Module will receive a serial data message from the Electronic Brake Control Module indicating that the brakes have been applied. If serial data communication is lost between the Lighting Control Module and the BCM or the Lighting Control Module and the EBCM, the Lighting Control Module will receive a voltage signal from the BCM to signal the brake lamps ON.