HVAC Control Module

Rear Defrost Switch: The scan tool displays On/Off. When the rear window defogger switch is pressed, the scan tool displays will momentarily display On.

Liftgate Module (LGM)

Defog Relay Voltage: The scan tool displays the voltage supplied to the rear defogger grid.

Rear Defog Requested: The scan tool displays Yes/No. When the window defogger switch is pressed, a request from HVAC control module is sent to LGM. This parameter indicates if the request was received.