Troubleshooting Hints - Interior Lights

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS
^ Always check for an open lamp filament before proceeding with diagnostics.
^ Check that grounds G200 and G400 are clean and tight.
^ Check for Body Control Module Diagnostic Trouble Codes (DTCs) 21/31 or 22/32 being set. Refer to Computers and Control Systems. Computers and Control Systems
^ 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 Troubleshooting Procedures). Diagnostic Aids
^ Refer to System Diagnosis.