Heated Glass Element: Description and Operation

Voltage to the Timer Relay is available at all times through the PWR ACC Circuit Breaker and the ORN/BLK (60) wire. Ground for the Timer Relay and the Rear Window Defogger Switch is provided through the BLK (150) wire connector (C238) at the Convenience Center.

With the Ignition Switch in RUN or START, voltage is available to the Timer Relay and the Rear Window Defogger Switch through the GAGES Fuse and the PNK/BLK (39) wire.

Momentarily closing the Rear Defogger Switch to the ON position allows current from the PNK/BLK (39) wire to flow through the Switch and the LT BLU (292) wire to the Timer Relay. This signal operates the Solid-State circuitry in the Timer Relay. Current from the PNK/BLK (39) wire flows through the relay coil and the relay contacts close. Current from the ORN/BLK (60) wire flow through the relay contacts and the PPL/WHT (293) wire to the Rear Defogger Switch ON Indicator and to the Rear Defogger Grid and ground G403 through the BLK (151) wire. The ON Indicator in the Rear Defogger Switch is illuminated whenever the system is in operation.

After about 10 minutes, the timer in the Timer Relay turns off, opening the relay contacts. Current flow to the Rear Defogger Grid stops.

The Rear Defogger system can be turned off before the end of the 10-minute timing period by moving the Rear Defogger Switch to the OFF position. This sends a momentary ground signal to the Timer Relay through the LT BLU (292) wire. This signal turns off the timing circuit and opens the relay contacts.

The Rear Defogger Switch is illuminated with the Light Switch in PARK or HEAD through the GRA (8) wire. Refer to the Lighting and Horn for Instrument Panel Lamps further information. Lighting and Horns