Troubleshooting Hints - Exterior Lights

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS
1. Check the LH MaxiFus(R) Block LCM/HDLP circuit breaker for continuity. If open, check for a short to ground in CKT 242 (RED).
2. Check the IP fuse block PARK LPS/INT LPS Fuse 6C by visual inspection. If open, check for a short to ground in CKT 240 (ORN).
3. Check the IP fuse block T/SIG/BU LP/BTSI Fuse 1B by visual inspection. If open, check for a short to ground in CKT 539 (PNK).
4. Check the IP fuse block BRK/HZRD LPS Fuse 6B by visual inspection. If open, check for a short to ground in CKT 140 (ORN).
5. Check the IP fuse block PERIMETER LT Fuse 8A by visual inspection. If open, check for a short to ground in CKT 1654 (TAN).
6. For Buick, check the IP fuse block PARK LP Fuse 8C by visual inspection. If open, check for a short to ground in CKT 9 (BRN).
7. If one of the turn indicators lights when the park lamps are turned on, check front park/turn lamp on that side.
8. If the turn lamps stay on (do not flash) in both left turn and right turn, replace the turn signal flasher.
9. If the hazard lamps stay on (do not flash) in during hazard function, replace the hazard flasher.
10. If a turn indicator does not light, but turn signals work, check bulb, connections, and wiring to indicator.
11. If only one light does not operate, check bulb, socket, and related wiring.
12. If Stoplamps do not turn OFF, adjust or replace Cruise/Shift Interlock/Brake Switch as necessary.
13. Check that grounds G104, G105, G201, G202 and G402 are clean and tight.
14. If any monitored exterior lamp is inoperative, but the adaptive lamp monitor (if equipped) does not indicate the outage, then refer to Lamp Monitor for diagnosis.
15. Before component replacement, check for poor connections at related component and in-line harness connector terminal connections.
16. Check for broken (or partially broken) wire inside of the insulation which could cause a system malfunction but prove good in a continuity/voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage drop with the system operational (under load).
17. Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems.
^ Refer to System Diagnosis.