Troubleshooting Hints

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Check Circuit Breaker 4. If open, check for short to ground in CKT 1640.
2. Check Fuse 11. If open, check for short to ground in CKT 39.
3. Check Rear Defogger Grid for opens, refer to Windows and Glass. Windows and Glass
4. Check that grounds G200, G201, G300 and G400 are clean and tight.
5. If both Mirror Defoggers are inoperative but Rear Defogger operates normally, check I/P Fuse 44. If Fuse 44 is open, check for a short to ground in CKT 676. If OK, perform Chart # 3. Chart #3 Both Mirror Defogger Inoperative
6. If Mirror Defoggers operate normally but Rear Defogger is inoperative, check that the Rear Defogger Grid connection is firmly mated and ground G300 (Sedan) or G400 (Wagon) is clean and tight. If OK, perform Chart # 5. Chart #5 Rear Defogger Inoperative
^ 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 after market electronic equipment which may affect the integrity of other systems refer Diagnostic Aids. Diagnostic Aids
^ Refer to System Diagnosis. System Diagnosis