Brake Lamp: Description and Operation

STOP LAMPS

The turn signal lamps are also used as stop lamps. The STOP/TURN fuse in the instrument panel (I/P) fuse block supplies battery positive voltage to the body control module (BCM) for the stop lamps.

The brake pedal position sensor is a resistive device 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 pressed. The brake pedal position sensor receives a low reference signal and a 10-volt reference voltage from the body control module (BCM) to supply a variable signal input directly to the BCM on the brake pedal position sensor signal circuit when the brakes are applied. When the signal reaches a voltage threshold indicating the brakes have been applied, the BCM then applies a battery positive voltage to the left rear and right rear stop/turn lamp supply voltage circuits to illuminate the stop lamps in the tail lamp assemblies and to the stop lamp supply voltage circuit to illuminate the center high mounted stop lamp (CHMSL). The stop lamps will operate when the ignition switch is not in the OFF position.

The stop lamp supply voltage circuit also supplies the powertrain control module (PCM) and the electronic brake control module (EBCM) for other functions, and is from a separate pin in the BCM connector. A short to ground or voltage on this circuit will also cause the stop lamps to operate incorrectly.