Diagnosis

TROUBLESHOOTING HINTS:
1. CHECK the condition of the GAUGES Fuse 4, CTSY LP Fuse 8, and PARK LPS Fuse 12. If any fuse(s) is open, LOCATE and REPAIR source of overload. REPLACE fuse(s).
2. CHECK that Grounds G200, G201, G202, G203, G420 and G450 are clean and tight.
3. CHECK for open filaments in inoperative lamps. If IP Compartment Box Lamp remains ON with the switch OFF, REPLACE the IP Compartment Box Lamp. If Underhood Reel Lamp remains On with the switch OFF, REPLACE the Underhood Reel Lamp
4. 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).
5. CHECK for proper installation of aftermarket electronic equipment which may affect the integrity of other systems. See Troubleshooting Procedures.

CIRCUIT OPERATION
Voltage is supplied at all times from the CTSY and LPS Fuses to the Courtesy Lamps, Dome and Reading Lamps, and IP Compartment Box Lamp. The Courtesy and Dome and Reading Lamps turn on when a ground path is provided by the Headlamp and Panel Dimmer Switch or one of the Door Jamb Switches. The IP Compartment Box Lamp and Vanity Lamps have switches that provide ground paths when the switches close.