Rear Window Defogger System Components
The rear window defogger system consist of the following components:
| • | HVAC control module |
| • | Body control module (BCM) |
| • | REAR DEFOG relay |
| • | Rear window defogger grid |
Rear Window Defogger Operation
Battery positive voltage is supplied to the REAR DEFOG relay switched input. The BCM supplies battery positive voltage to REAR DEFOG relay coil. When you depress the rear window defogger switch, the HVAC control module illuminates the rear window defogger indicator and grounds the control circuit of the REAR DEFOG relay. This energizes the REAR DEFOG relay and allows battery positive voltage through the switch contacts of the relay through the REAR DEFOG circuit breaker to the rear window defogger grid. Ground for the rear window defogger is provided by G309.
The rear defogger will remain on for a maximum of 20 minutes, at which point the HVAC control module will interrupt defog functions.
If battery voltage is low, the BCM will disable the rear window defogger by removing the battery positive voltage supplied to the REAR DEFOG relay coil.
