Rear Defogger System Components
The rear window defogger system consist of the following components:
| • | A body control module (BCM) |
| • | A rear window that has a number of grid lines |
| • | Two bus bars that are attached to the inside surface of the rear
window. |
The battery voltage terminal and ground terminal are soldier to the
bus bars.
Rear Window Defogger Operation
Battery positive voltage is supplied through the BODY 2 fuse in the
LH underhood fuse block to the REAR DEFOGGER relay switch. OFF/RUN voltage
is supplied through the IGN0-BODY fuse to the REAR DEFOGGER relay
coil. When you start the engine, and depress the rear window defogger
switch. The HVAC control module sends a class 2 message to the BCM
to enable the rear window defogger system. The BCM energizes the REAR
DEFOGGER relay by grounding the control circuit of the relay. This allows
battery positive voltage to the rear window defogger. The BCM then sends
a class 2 message to the HVAC control module requesting the illumination
of the rear window defogger indicator. The HVAC control module illuminates
the rear window defogger indicator. Ground for the rear window defogger
is provided by G401.
When you turn ON the ignition and press the rear window defogger switch
for the first time, the defogger cycle lasts 10 minutes. Further operation
results in 5 minute defogger cycles. The defogger cycle resets
to 10 minutes when you cycle the ignition to the OFF position
and then back to the ON position.
