Heated Glass Element: Testing and Inspection

ELECTRIC BACKLIGHT (EBL) SYSTEM

NOTE: Illumination of the defogger switch indicator lamp does not necessarily mean that electrical current is reaching the rear window glass and/or the outside rear view mirror heating grids (when equipped).

NOTE: See Wiring Information for circuit descriptions and diagrams of the rear window defogger and heated mirror systems.

Operation of the Electric Backlight (EBL) system can be confirmed by the following:






NOTE: Typical heated rear window glass shown.

1. Use a scan tool and check for Diagnostic Trouble Codes (DTCs) related to the A/C-heater control and the Totally Integrated Power Module (TIPM). If no DTCs are found, go to 2. If any DTCs are found, repair as required, then proceed to 2.
2. Turn the ignition switch to RUN. Press the rear window defogger switch to the On position. Rear window defogger operation can be checked by feeling the surfaces of the rear window glass, or the heated outside rear view mirror glass when equipped with heated mirrors. A distinct difference in temperature between the grid lines (5) and the adjacent clear glass or the heated mirror glass 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 RUN.
- Confirm that the rear window defogger switch is pressed to the On position.
- Confirm that the EBL feed wire (3) is connected to the heating grid positive terminal and that there is continuity between the EBL relay terminal and the heating grid.
- Confirm that the EBL ground wire (6) is connected to the heating grid negative terminal and that there is continuity to ground.
- Check fuses J14, M11 and M34 located in the TIPM. Fuses must be operational and correctly installed in the fuse receptacle with the electrical connections secure.
- When diagnosing a heater mirror concern, check fuse M35 located in the TIPM. The fuse must be correctly installed in the fuse receptacle with the electrical connections secure.

4. 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) Service and Repair.
5. If proper EBL system operation has been verified, but the EBL indicator lamp in the control knob does not illuminate, replace the A/C-heater control A/C And Heater Control - Removal.