GM Service Manual Online
For 1990-2009 cars only

Body Control Module (BCM)

HVAC Rear Defog Switch: The scan tool displays Active or Inactive. This data parameter is used for the HVAC system with C60. When the rear defogger switch is depressed, the scan tool will display Active. When the switch is depressed again, the scan tool will display Inactive.

Rear Defog Relay: The scan tool displays Active or Inactive. When the BCM energizes the RR DEFOG relay, the scan tool will display Active. When the BCM de-energizes the RR DEFOG relay, the scan tool will display Inactive.