Electric Backlight System

DIAGNOSIS AND TESTING - ELECTRIC BACKLIGHT (EBL) SYSTEM

NOTE: Illumination of the defogger switch indicator lamp does not necessarily mean that electrical current is reaching the rear glass heating grid lines.

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

Operation of the rear window defogger (Electric Back Light) (EBL) system can be confirmed by the following:





1. Use a scan tool and check for Diagnostic Trouble Codes (DTCs) related to the U-Connect Touch (TM) screen module, Telematics Gateway (TGW) or the A/C heater module. If no DTCs are found, go to 2. If any DTCs are found, repair as required, then proceed to 2.
2. With the ignition in the Run position, press 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, 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 Direct Current (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 the ignition is the Run position.
- Confirm the rear window defogger switch is on.
- Confirm the EBL feed wire (3) is connected to the heating grid positive terminal and that there is continuity between the heating grid and the EBL relay in the Power Distribution Center (PDC).
- Confirm the EBL ground wire (6) is connected to the heating grid negative terminal and that there is continuity to ground.
- Check the EBL fuse in the PDC. The fuse must be tight in its receptacle and its electrical connections must be secure.

4. If broken defogger grid lines or bus bars are suspected, use a 12 volt Direct Current (DC) voltmeter and contact the rear glass heating grid ground terminal A with the negative lead and each rear glass heating grid line at its mid-point (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 the EBL system operation has been verified but the rear window defogger indicator lamp in the switchbank does not illuminate, replace the entire switchbank pod Instrument Cluster Switch Pod - Removal.