Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Problem Symptoms Table
HINT:
The window defogger system is part of the large-scale multiplex communication system. This system features shared communication wiring that reduces the wiring complexity of the communication lines. The first step in any repair is to confirm the proper operation of the communication system. Proceed with troubleshooting after the communication has been verified (see the multiplex communication system).
Window defogger system
| Symptom | Suspected area | Refer To |
|---|---|---|
| Rear window defogger does not operate (Indicator ON) | 1. DEF H-fuse | WINDOW DEFOGGER SYSTEM |
| 2. A/C (HTR) fuse | WINDOW DEFOGGER SYSTEM | |
| 3. GAUGE fuse | WINDSHIELD GLASS | |
| 4. DOME fuse | WINDSHIELD GLASS | |
| 5. ECU-B fuse | WINDSHIELD GLASS | |
| 6. DEF relay | DEFOGGER RELAY | |
| 7. Rear window defogger wire | WINDOW DEFOGGER WIRE | |
| 8. Wire harness | - | |
| Rear window defogger does not operate (Indicator OFF) | 1. DEF H-fuse | WINDOW DEFOGGER SYSTEM |
| 2. A/C (HTR) fuse | WINDOW DEFOGGER SYSTEM | |
| 3. GAUGE fuse | WINDOW DEFOGGER SYSTEM | |
| 4. DOME fuse | WINDOW DEFOGGER SYSTEM | |
| 5. ECU-B fuse | WINDOW DEFOGGER SYSTEM | |
| 6. DEF relay | DEFOGGER RELAY | |
| 7. Combination meter | HOW TO PROCEED WITH TROUBLESHOOTING | |
| 8. Steering pad switch | WINDOW DEFOGGER SYSTEM | |
| 9. Multi-display assembly | HOW TO PROCEED WITH TROUBLESHOOTING | |
| 10. Rear window defogger wire | WINDOW DEFOGGER WIRE | |
| 11. Wire harness | - | |
| Mirror heater does not operate (Indicator ON) | 1. M/HTR fuse | WINDOW DEFOGGER SYSTEM |
| 2. A/C (HTR) fuse | WINDOW DEFOGGER SYSTEM | |
| 3. GAUGE fuse | WINDOW DEFOGGER SYSTEM | |
| 4. DOME fuse | WINDOW DEFOGGER SYSTEM | |
| 5. ECU-B fuse | WINDOW DEFOGGER SYSTEM | |
| 6. Mirror heater relay | MIRROR HEATER RELAY | |
| 7. Outer rear view mirror assembly | OUTER REAR VIEW MIRROR | |
| 8. Wire harness | - | |
| Mirror heater does not operate (Indicator OFF) | 1. M/HTR fuse | WINDOW DEFOGGER SYSTEM |
| 2. A/C (HTR) fuse | WINDOW DEFOGGER SYSTEM | |
| 3. GAUGE fuse | WINDOW DEFOGGER SYSTEM | |
| 4. DOME fuse | WINDOW DEFOGGER SYSTEM | |
| 5. ECU-B fuse | WINDOW DEFOGGER SYSTEM | |
| 6. Mirror heater relay | MIRROR HEATER RELAY | |
| 7. Combination meter | HOW TO PROCEED WITH TROUBLESHOOTING | |
| 8. Steering pad switch | WINDOW DEFOGGER SYSTEM | |
| 9. Multi-display assembly | HOW TO PROCEED WITH TROUBLESHOOTING | |
| 10. Outer rear view mirror assembly | OUTER REAR VIEW MIRROR | |
| 11. Wire harness | - |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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