Heated Glass Element: Description and Operation

Circuit Operation
Voltage is applied at all times through fuse C-17 to the rear defogger relay contact. With the starter switch in ON or START voltage is applied through fuse C-4 to the rear defogger switch and the rear defogger relay coil.

When the rear defogger switch is pushed, a voltage is detected at connector B6 pin 8 of the alarm and relay control unit, and provides ground at connector B7 pin 5 for the rear defogger relay coil and the rear defogger "ON" indicator light. The rear defogger relay energizes and the relay contact closes. Battery voltage is then applied to the rear defogger. The indicator remains illuminated and the rear defogger heats the rear window to remove any fog from the glass. The rear defogger will turn off automatically after approximately 30 minutes. It will also turn off if the starter switch is turned to OFF or if the rear defogger switch is depressed again.