Rear Window Defogger System Components
The rear window defogger system consist of the following components:
| • | HVAC control assembly |
| • | Body control module (BCM) |
| • | Rear Defog relay |
| • | Rear window defogger grid |
Rear Window Defogger Operation
Battery positive voltage is supplied through the BATT 3 fuse in the underhood fuse block, to the Rear Defog relay switched input. With the engine started, the BCM supplies battery positive voltage to Rear Defog relay coil. When you depress the rear window defogger switch the HVAC control assembly illuminates the rear window defogger indicator and energizes the Rear 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 G403.
When you start the engine and press the rear window defogger switch for the first time, the defogger cycle lasts for 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 start the engine.
If the battery voltage is very low, the rear defogger feature is disabled.
