Heated Glass Element: Description and Operation

Rear Window Defogger:

REAR WINDOW DEFOGGER SYSTEM
The rear window defogger is used to defog and deice the rear window in cases of freeze up and humid conditions. The switch is located within the mode select knob on the HVAC control module

The system consists of a rear glass with two vehicle bus bars and a series of electrically connected grid lines on the inside surface. The control switch is located in the HVAC control Module. The relay is located in the junction block. The timer is located in the Body Control Module (BCM).

Circuit protection for heated grid is provided by:
- Fuse 12 (EBL) located in the power distribution center
- Rear window defogger relay (EBL) located in the Junction Block

When the button is depress to the ON position, current is directed to the rear defogger grid lines. A yellow indicator within the center of the button will illuminate while the defogger is ON. The heated grid lines will heat the rear glass and clear the window surface of fog or frost.

CAUTION: Grid lines can be damaged or scraped oft with sharp instruments, care should be taken in cleaning glass or removing foreign materials, decals or stickers. Normal glass cleaning solvents or hot water used with rags or toweling is recommended.

HVAC Control Module:

HVAC CONTROL MODULE
The rear window control switch and circuit are integrated into the HVAC control module.

When actuating the switch it sends a ground signal to the Body Control Module (BCM). The BCM actuates the relay allowing current to flow through the grid lines for ten minutes upon initial actuation. Then 5 minutes with each subsequent actuation or until either the switch or ignition is turned OFF. An indicating lamp illuminates the rear window defogger switch.