Troubleshooting Hints - Exterior Lights

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS
1. Check the LH MaxiFuse(R) block BODY 1 Fuse by visual inspection. If open, check for a short to ground in CKT 1342 (RED).
2. Check the engine compartment fuse/relay center HAZARD Fuse by visual inspection. If open, check for a short to ground in CKT 740 (ORN).
3. Check the engine compartment fuse/relay center STOP Fuse by visual inspection. If open, check for a short to ground in CKT 1540 (ORN).
4. Check the engine compartment fuse/relay center CNR LP Fuse by visual inspection. if open, check for a short to ground in CKT 241 (BRN).
5. Check the rear compartment fuse block LT PARK Fuse by visual inspection. If open, check for a short to ground in CKT 9 (BRN/WHT) (DeVille) or CKT 9 (BRN) (Eldorado).
6. Check the rear compartment fuse block RT PARK Fuse by visual inspection. If open, check for a short to ground in CKT 9 (BRN).
7. Check the rear compartment fuse block TURN Fuse by visual inspection. If open, check for a short to ground in CKT 141 (BRN).
8. Check that grounds G101, G201, G205, G401 and G402 are clean and tight.
9. If the LH park lamps are inoperative, check for an open in CKT 9 (BRN/WHT) (DeVille) or CKT 9 (BRN) (Eldorado) between the rear compartment fuse block and S412.
10. If the RH park lamps are inoperative, check for an open in CKT 9 (B RN) between the rear compartment fuse block and S411.
11. If the LH front turn lamps and turn indicator are inoperative, check for an open or short to ground in CKT 14 (LT BLU) between the turn/hazard switch and S206.
12. If the RH front turn lamps and turn indicator are inoperative, check for an open or short to ground in CKT 15 (DK BLU) between the turn/hazard switch and S205.
13. If the LH rear turn lamps are inoperative, check for an open or short to ground in CKT 18 (YEL) between the turn/hazard switch and S415, S457, or the LH tail/turn lamp.
14. If the RH rear turn lamps are inoperative. check for an open or short to ground in CKT 19 (DK ORN) between the turn/hazard switch and S416, S458, or the RH tail/turn lamp.
15. If the turn lamps flash faster than normal, check for a burned out bulb. If all bulbs are OK, replace the turn signal flasher.
16. If one of the turn indicators goes on when the park lamps are turned on, check the front park/turn lamps on that side for an open or poor connection.
17. If turn lamps stay on (do not flash) in both left turn and right turn positions, replace the turn signal flasher.
18. If hazard lamps stay on (do not flash) during the hazard operation but stop lamps operate normally, replace the hazard flasher.
19. For any of the following symptoms, replace the turn/hazard switch:
^ Turn signal lamps will not turn on or off.
^ All turn/hazard/stop lamps do not work and C202 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.
20. If stop lamps do not turn off, adjust or replace the stoplamp/BTSI switch.
21. If a turn indicator does not light but the turn signal works, check the bulb, connections and wiring to the indicator (see schematic).
22. If only one lamp does not operate, check the lamp, socket and related wiring for an open (see schematic).
23. If park lamps stay on and headlamps light at full intensity with daylight conditions, check for an obstruction covering the ambient light sensor. Refer to Headlights. Headlamp
24. Before component replacement. check for poor connections at related component and in-line harness connector terminal connections.
25. 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).
26. Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems.