Heated Glass Element: Description and Operation

Rear Window Defogger:

(Typical) Heated Windshield Wiper De-icer:

HEATED GLASS
The electrically heated Rear Window Defogger, Heated Power Side View Mirrors, and Heated Windshield Wiper De-icer is available on select models.

The Rear Window Defogger (Refer to ELECTRICAL/HEATED GLASS - DESCRIPTION) system consists of two vertical bus bars linked by a series of grid lines on the inside surface of the rear window. The electrical circuit consists of the rear defogger switch in the HVAC control assembly and a relay with timer switch to turn OFF the system after ten minutes. The main feed circuit is protected by fuse 13 (40 amp) in the Power Distribution Center (PDC) which is connected directly to the Front Control Module (FCM) to form an integrated unit called an Integrated Power Module (IPM). The rear defogger switch and relay also activates the heated power side view mirrors. The rear defogger switch also activates the heated windshield wiper de-icer which is powered by the RUN/ACC relay in the IPM and feed thru fuse # 11 (20 amp) in the PDC. The heated mirror circuit is protected by a non-servicable Positive Temperature Coefficient (PTC) located inside the PDC. The heated windshield wiper de-icer circuit is protected by fuse 11 (20 amp) in the PDC.

The Heated Windshield Wiper Deicer is also activated when the DEFROST mode is selected on the HVAC. In the DEFROST mode the rear defogger time-out is bypassed, the heated windshield wiper deicer will stay ON until the another mode is selected. For circuit information and component location refer to appropriate section for Wiring Diagrams.

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

DEFOGGER RELAY
There is no heated windshield wiper de-icer relay. The grid is powered directly from fuse # 11 in the PDC and is controlled directly from the HVAC control assembly.

Fig.3 HVAC Control Panel:

REAR WINDOW DEFOGGER / HEATED MIRROR / FRONT WIPER DE-ICE
The rear window defogger switch is integrated into the HVAC control panel assembly. The defroster button controls the rear window defogger, heated side view mirrors and front wiper de-icer grid. In addition the front wiper de-ice function is turned on when front defog/defrost mode is selected.

A LED indicator will illuminate when the switch is activated. The switch energizes the HVAC control assembly when it requests the Front Control Module (FCM) to activate the rear window defogger relay The relay controls the current to flow to the grids of the rear window defogger, heated power side view mirrors and the heated windshield wiper de-icer. The defogger relay will be ON for approximately 10 minutes or until the control switch or ignition is turned OFF.

When the defroster button is pushed, the HVAC control sends a bus message over the PCI bus to the Front Control Module (FCM) which controls the Rear Window Defogger relay. The defroster LED will illuminate when the defroster function is on. The defroster will function for 10 minutes or can be cycled off sooner by pressing the defroster button again. The front wiper de-icer grid receives its 12 volts from the accessory relay through fuse 11 and the HVAC control module supplies the grid ground.