Heated Glass Element: Testing and Inspection
ELECTRIC BACKLIGHT (EBL) SYSTEMNOTE:
- Illumination of the defogger switch indicator lamp does not necessarily mean that electrical current is reaching the rear glass heating grid lines.
- For circuit descriptions and diagrams of the rear window defogger system, refer to WIRING DIAGRAM INFORMATION.
Operation of the electrical backlight (EBL) system can be confirmed by the following:
1. Using a scan tool, check for diagnostic trouble codes (DTCs) related to the A/C-heater control and the front control module (FCM). If no DTCs are found, go to Step 2. If any DTCs are found, repair as required, then proceed to Step 2
2. Turn the ignition switch to the On position. Set the rear window defogger switch in the Run position. The rear window defogger operation can be checked by feeling the rear window glass or the heated outside rear view mirror glass. A distinct difference in temperature between the grid lines (5) and the adjacent clear glass or the mirror glass (when equipped with heated mirrors) should be detected within three to four minutes of operation.
3. If a temperature difference is not detected, use a 12-volt DC voltmeter and contact the rear glass heating grid terminal A (1) with the negative lead, and terminal B (2) with the positive lead. The voltmeter should read battery voltage. If the voltmeter does not read battery voltage, check the following:
- Confirm that the ignition switch is in the On position.
- Make sure that the rear glass heating grid feed wire (3) and ground wire (6) are connected to the terminals. Confirm that the ground wire has continuity to ground.
- Check the EBL relay and fuses located in the integrated power module (IPM) in the engine compartment. The relay and fuses must be tight in their receptacles and all electrical connections must be secure. Refer to the appropriate wiring information for diagnosis and testing of the ISO-standard relay.
When the above steps have been completed and the rear glass heating grid is still inoperative, one or more of the following is faulty:
- Rear window defogger switch in the A/C-heater control.
- Rear window defogger grid lines (all grid lines would have to be broken, or the power feed or the ground wire disconnected, for the entire heating grid to be inoperative).
4. If the EBL system operation has been verified but the rear window defogger indicator does not illuminate, replace the A/C-heater control.
5. If broken defogger grid lines or bus bars are suspected, use a 12-volt DC voltmeter and contact terminal A with the negative lead and each rear glass heating grid line at its mid-point C (4) with the positive lead. The voltmeter should read approximately 6 volts at each grid line mid-point. If the voltmeter does not read approximately 6 volts, repair the open grid line(s) or bus bar(s).