Troubleshooting Hints - Interior Lights Dimming

TRY FOLLOWING CHECKS BEFORE DOING SYSTEM CHECK
1. Make sure Park Lamps turn "ON" and "OFF" normally before proceeding with System Diagnosis. Refer to Exterior Lamps for Park Lamp diagnosis. Testing and Inspection
2. Check Trunk Compartment Fuse Block Fuse D13 by visual inspection.
3. Check Trunk Compartment Fuse Block Fuse D11 by visual inspection (Deville/Concours).
4. Check Trunk Compartment Fuse Block Fuse C5 by visual inspection (Export).
5. If only one lamp does not light, check bulb, socket and related wiring (see schematic).
6. Check that grounds G301, G302 (Eldorado/Seville), G304 (DeVille/Concours/Seville) and G401 (Seville) are clean and tight.
7. 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).
8. Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems.
9. Before component replacement, check for poor connections at related component and in-line harness connector terminal connections.
^ Refer to System Check for a guide to normal operation.
^ Refer to Symptom Table for diagnostic tests.