Heated Glass Element: Description and Operation

When the Ignition Switch is turned to "RUN," voltage is applied from Fuse 3 to the Rear Defogger Switch. When the Rear Defogger Switch is turned to "ON," voltage is momentarily applied to the Rear Defogger Solid State Timer through CKT 241. With voltage applied to the Rear Defogger Timer On/Off Input, the Solid State Timer will energize the Internal Relay which applies voltage to the Rear Defogger Grid. The Relay remains closed until the defog cycle is complete or the Rear Defogger Switch/Timer is turned "OFF.

When the internal contacts of the Rear Defogger Relay are closed, voltage from Circuit Breaker 12 is applied to the indicator and to CKT 293.

The Rear Defogger Switch contains an internal timer to control the time the internal contacts are closed. When the Ignition Switch is turned to "RUN" and the Rear Defogger Switch is turned to "ON" for the first time, the defog cycle lasts 10 minutes. Further operation will result in 5 minute defog cycles. The defog cycle is reset to 10 minutes when the Ignition Switch is turned to "OFF" and back to "RUN."