Rear Window Defogger System Components
The rear window defogger system consist of the following components:
| • | Body control module (BCM) |
| • | Rear window that has a number of grid lines |
Rear Window Defogger Operation
When you turn the ignition to the ON position, ignition voltage is
supplied to the DEFOG relay coil. Battery positive voltage is supplied
at all times to the DEFOG relay switched input. When the rear window
defogger switch is depressed, the HVAC control module illuminates
the rear window defogger indicator and sends a class 2 message to
the BCM. The BCM energizes the DEFOG relay by grounding the control circuit
of the relay. This allows battery positive voltage from the relay
switched input through the switch contacts and out the relay switched output
to the rear window defogger. Ground for the rear window defogger
is provided by G306. If the vehicle is equipped with cargo doors, ground
for the rear window defoggers will be provided by G410.
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.
