Scan Tool Data Definitions - Body Control Module (BCM)

Rear Defog Output: The scan tool displays On/Off. When the rear window defogger is enabled, the Heater and A/C Programmer sends a class 2 message to the Body Control Module to enable the rear defogger. The Body Control Module energizes the HTD BK LITE relay by grounding the control circuit of the relay, which the scan tool displays as On.