Brake Lamps

NOTE:

The rear lamp units and the CHMSL are illuminated by several LED units that are soldered to the electronic circuit boards within the lamp housings. The brake lamps are powered by high side drivers within the BCM based upon an input to the CAB from the brake pedal position sensor. If all of the LED units within the CHMSL fail to operate, diagnose and repair the brake lamps before attempting to repair the CHMSL. If the brake lamp LED units in the rear lamps operate but none of the CHMSL LED units illuminate, test and repair the CHMSL ground or feed circuit if required. If some of the rear lamp or CHMSL LED units operate and others do not, the outer rear lamp or CHMSL assembly must be replaced with a new unit.

CONDITION	POSSIBLE CAUSES	CORRECTION
BRAKE LAMP DOES NOT ILLUMINATE	1. Ineffective ground circuit.	1. Test and repair open brake lamp ground circuit if required.
	2. Ineffective fuse.	2. Test and replace the fuse if required.
	3. Ineffective feed circuit.	3. Test and repair open stop lamp output circuit if required.
	4. Ineffective brake pedal position sensor.	4. Test and replace brake pedal position sensor if required.
	5. Ineffective CAB inputs or outputs.	5. Use a diagnostic scan tool to test the CAB inputs and outputs. Refer to the appropriate diagnostic information.
	6. Ineffective BCM inputs or outputs.	6. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information.
BRAKE LAMP DOES NOT EXTINGUISH	1. Ineffective feed circuit.	1. Test and repair shorted stop lamp output circuit if required.
	2. Ineffective brake pedal position sensor.	2. Test and replace brake pedal position sensor if required.
	3. Ineffective CAB inputs or outputs.	3. Use a diagnostic scan tool to test the CAB inputs and outputs. Refer to the appropriate diagnostic information.
	4. Ineffective BCM inputs or outputs.	4. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information.