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Mysteries of the Rear Defroster

new 1/20/2004


Here's how it works:

The heated back window switch and light (18C621):
a.. is an integral part of the integrated control panel.
b.. sends a momentary ground signal to the generic electronic module (GEM)
when activated.
c.. GEM then sends a ground signal to the heated back window relay,
supplying power to the heated back window grid and heated side mirrors.
d.. GEM starts the 10 minute time-out function. At the end of 10 minutes,
the GEM will discontinue the ground supply to the heated back window relay.
A second press of the heated back window switch and light will cause GEM to
discontinue ground signal to heated back window relay turning the system
OFF.
e.. if the GEM time-out function has started, and the ignition switch is
turned to START the GEM timing is interrupted and will resume when ignition
switch is turned to RUN.
f.. Turning the ignition switch to OFF position will cancel GEM time-out
function.
Glen Murdock
Port Lavaca, TX

Well I know that sure clears it up for me. Gonna sleep much better tonight. Thanks, Glen!!

U.L.


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