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 ABS module 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. | Use the scan tool to check for fault codes. If fault codes are found, repair as needed and retest. If no fault codes are present, perform the diagnostics steps listed for code C0042-28-BRAKE PEDAL POSITION SENSOR - SIGNAL BIAS LEVEL OUT OF RANGE / ZERO ADJUSTMENT FAILURE . Refer to DIAGNOSTIC CODE INDEX . |
| 2. Ineffective fuse. | ||
| 3. Ineffective feed circuit. | ||
| 4. Ineffective brake pedal position sensor. | ||
| 5. Ineffective ABS module inputs or outputs. | ||
| 6. Ineffective BCM inputs or outputs. | ||
| BRAKE LAMP DOES NOT EXTINGUISH | 1. Ineffective feed circuit. | Use the scan tool to check for fault codes. If fault codes are found, repair as needed and retest. If no fault codes are present, perform the diagnostics steps listed for code C0042-2A-BRAKE PEDAL POSITION SENSOR - STUCK. Refer to DIAGNOSTIC CODE INDEX . |
| 2. Ineffective brake pedal position sensor. | ||
| 3. Ineffective ABS module inputs or outputs. | ||
| 4. Ineffective BCM inputs or outputs. |