Heated Glass Element: Description and Operation

CIRCUIT OPERATION
With the Ignition Switch in RUN, voltage is applied to the Rear Defogger Control. When the Rear Defogger Switch is pressed, a momentary voltage is applied to the Rear Defogger Timer-Relay. The contact closes, which provides voltage to the On Indicator and the Rear Defogger. The rear window will become warm to remove fog from the surface of the window.

The contact in the Rear Defogger Control will stay closed until the Rear Defogger Control switched is turned off, or the timer cycle is complete.

The first time the Rear Defogger switch is pressed, the Timer-Relay will allow the Rear Defogger to operate for 10 minutes. After the first operation, the Timer-Relay will allow the Rear Defogger to operate for a maximum of 5 minutes each time after the Rear Defogger Switch is pushed in. The Timer-Relay will reset to 10 minutes when the Ignition Switch is turned OFF and then back to the RUN position.

The Timer-Relay also shuts off at any time when the Rear Defogger Control switch is pressed before the timer cycle is complete.