Electric Backlight (EBL) and Mirror System

DIAGNOSIS AND TESTING - ELECTRIC BACKLIGHT (EBL) AND HEATED MIRROR 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.

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) and heated mirror systems can be confirmed by the following:





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. Set the rear window defogger switch to ON. 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 (1) and the adjacent clear glass (2) or the heated mirror glass should be detected within 3 to 4 minutes of operation.
3. If a rear window glass temperature difference is not detected, use a 12-volt DC voltmeter (4) and contact the rear glass heating grid power feed terminal A (3) with the positive lead, and the ground terminal B (5) 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 ON.
- 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.
- When diagnosing a heated mirror concern, check the heated mirror circuit fuse located in the TIPM. The fuse must be tight in the receptacle and all electrical connections must be secure.

4. If broken defogger grid lines or bus bars are suspected, use a 12-volt DC voltmeter and contact the rear glass heating grid ground terminal B with the negative lead and each rear glass heating grid line at its mid-point 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 the operation of the EBL system and/or the heated mirror system has been verified but the defogger LED indicator does not illuminate, replace the A/C-heater control A/C And Heater Control - Removal.