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 Window Defogger Grid for opens.
4. Check that grounds G200, G201, G300 and G400 are clean and tight.
5. If both Mirror Defoggers are inoperative but Rear Window 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 Heated Mirrors Are Inoperative
6. If Mirror Defoggers operate normally but Rear Window Defogger is inoperative check that the Rear Window 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 Window Defogger Inoperative
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "G00D" 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 "General Troubleshooting Procedures,"). Diagnostic Aids
^ Refer to System Diagnosis. System Diagnosis