S10/T10 P/U 2WD V6-262 4.3L VIN W CPI (1992)
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 and Ground G102.
With the Ignition Switch in RUN or START, voltage is available to the Timer Relay and the Rear Window Defogger Switch through the IGN/GAU
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 flows through the relay contacts and the PPL/WHT (293) wire
to the Rear Defogger Switch ON Indicator and to the Rear Defogger Grid and G425 through the BLK (150) wire. The ON Indicator in the Rear
Defogger Switch is lit whenever the system is in operation.
After about 10 minutes, the timer in the Timer Relay turns off, opening the relay contacts. Current flows 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 lit with the Light Switch in PARK or HEAD through the GRA (8) wire. Refer to the Instrument Panel Lamps for further
information.
