GM Service Manual Online
For 1990-2009 cars only

Outside Mirror Description and Operation Heated Mirrors

Heated OSRV Mirror

On vehicles equipped with heated outside rearview mirrors (OSRV), the driver door module (DDM) and passenger door module (PDM) controls the activation of the mirror heaters. Upon receiving a Class 2 message indicating a request for heated mirrors, the DDM (and PDM for the passenger side) will activate the mirror heater output. The mirror heaters will remain active until a new message is received indicating rear defogger is to be deactivated (either by driver input or by expiration of a calibrated timer).