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 (EBL) and heated mirror systems,

Operation of the Electrical Back Light (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 rear window glass (1), or the heated outside rear view mirror glass when equipped with heated mirrors. A distinct difference in temperature between the grid lines (2) or the heated mirror glass and the adjacent clear glass should be detected within 3 to 4 minutes of operation.
3. If a temperature difference is not detected, use a 12-volt DC voltmeter (6) and contact the rear glass heating grid terminal A (5) with the positive lead, and terminal B (7) with the negative lead. The voltmeter should read battery voltage. If the voltmeter does not read battery voltage, check the following:
- Confirm the ignition switch is in RUN.
- Confirm the rear window defogger switch is in the on position.
- Confirm the EBL feed wire is connected to the heating grid positive terminal and that there is continuity between the TIPM and the heating grid.
- Confirm the EBL ground wire is connected to the heating grid negative terminal and that there is continuity to ground.
- Check fuse J14 (40 amp) and fuse M34 (10 amp) located in the TIPM. The fuses must be tight in the receptacles and the electrical connections muse be secure.
- Check the EBL relay located in the TIPM. The relay must be tight in the receptacle and the electrical connections muse be secure.
- When diagnosing a heated mirror concern, check the fuse M35 (10 amp) located in the TIPM. The fuse must be in the receptacle and the electrical connections must be secure.

4. If broken defogger grid lines or bus bars (3) are suspected, use a 12-volt DC voltmeter and contact terminal B 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 EBL system operation has been verified but the rear window defogger indicator does not illuminate, replace the A/C-heater control A/C and Heater Control - Removal.