Heated Glass Element: Testing and Inspection

Electrically heated rear window defogger or the heated windshield wiper deicer operation can be checked on the vehicle in the following manner:
1. Turn the ignition switch to the ON position.
2. Using a ammeter on the battery, turn the rear defogger control switch to the ON position, a distinct increase in amperage draw should be noted.
3. The rear window defogger or the heated windshield wiper deicer operation can be checked by feeling the glass. A distinct difference in temperature between the grid lines and adjacent clear glass can be detected in 3 to 4 minutes of operation.

Grid Line Test:

4. Using a DC voltmeter contact terminal B with the negative lead, and terminal A with the positive lead. The voltmeter should read 10 - 14 volts.
5. Indicator light illumination means that there is power available at the switch only and does not necessarily verify system operation.
6. If turning the defogger switch ON, no distinct current draw on the ammeter the problem should be isolated in the following manner:
- Confirm that ignition switch is ON.
- Ensure that the heated rear window or the heated windshield wiper deicer feed pigtail is connected to the wiring harness and that the ground pigtail is in fact grounded.
- Ensure that the proper fuse in the PDC is OK.
7. When the above steps have been completed and the system is still inoperative it may be necessary to connect a DRB III scan tool and refer to the Diagnostics, you may also check for the following being defective:
- HVAC control assembly
- Rear window defogger relay in the IPM.
- Check for loose connector or a wire pushed out of connector.
- Rear window or the windshield grid lines (all grid lines would have to be broken, or one of the feed pigtails not connected to the bus bar, for no ammeter deflection).
8. If turning the switch ON produces severe voltmeter deflection, the circuit should be closely checked for a shorting condition.
9. If the system operation has been verified but indicator LED does not light, replace the HVAC control assembly.
10. For detailed wiring information, refer to the Wiring Diagrams.