Body Control Module (BCM)

Rear Defog Output: The scan tool displays On/Off. When the rear window defogger is enabled, the HVAC control module sends a message on the to the IPM requesting the activation the rear window defogger. The IPM sends a class 2 message to the BCM to enable the rear window defogger system. The BCM energizes the HTD BK LITE relay by grounding the control circuit of the relay, which the scan tool displays as On.