Troubleshooting Hints - Exterior Lights

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS
1. If the Turn Lamps or Backup Lamps do not work, check I/P Fuse #12. If open, check for short to ground in CKT 239.
2. If the Stop Lamps or Hazard Lamps do not work, check I/P Fuse #37. If open, check for short to ground in CKT 140.
3. If one of the Turn Indicators goes on when the Park Lamps are turned on, check the Park and Front Side Marker Lamp on that side for open or poor connection.
4. If Turn Lamps stay on (do not flash) in both Turn Left and Turn Right, replace the Turn Flasher.
5. For any of the following symptoms, replace the Turn Signal Switch:
^ Turn Signal Switch will not turn "ON/OFF."
^ All Turn/Hazard/Stop Lamps do not work and C210 is firmly mated.
^ Some Turn Lamps work and all Hazard Lamps work.
^ Some Hazard Lamps work and all Turn Lamps work.
^ Hazard Lamps do not turn "OFF."
6. If Hazard Lamps stay on (do not flash) in "Hazard," but Stop Lamps operate normally, replace the Hazard Flasher.
7. If Stop Lamps do not turn "OFF" adjust/replace the Stoplamp Switch.
8. If a Turn Indicator does not light but the Turn Signal works, check the bulb, connections and wiring to the Indicator. Refer to Instrument Cluster (Buick) or (Chevrolet). Testing and Inspection
9. If only one lamp does not operate, check the lamp, socket and related wiring for opens or corrosion (see schematic).
10. With Twilight Sentinel, if Parking Lamps stay on and Headlamps stay at full intensity with daylight conditions check for an obstruction covering the Twilight Sentinel Photocell (See Headlamps With Twilight Sentinel). Headlamp
11. If one Front Park and/or Marker Lamp does not light, check that its ground is clean and tight.
12. If none of the Park/Taillamps work, check I/P Fuse #31. If open, check for short to ground in CKT 240.
13. If Park Lamps do not turn "OFF," check Headlamp Switch. If OK, repair short to B+ in CKT 9.
14. Sedan: If License Lamp is inoperative, check for open in CKT 750 between S408 and lamp socket. Check for open in CKT 1256 between S417 and lamp socket. Wagon: If one License Lamp is inoperative, check for open in CKT 750 between S403 and inoperative lamp socket. Check for open in CKT 1256 between S409 and inoperative lamp socket.
^ Check for a broken (or partially broken) wire inside of the insulation which could cause 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).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (refer to General Troubleshooting Procedures). Diagnostic Aids
^ Refer to System Diagnosis.