I have a 99 D2 with a heated front screen, or rather it had a heated screen from the factory but the previous owner replaced it with a non-heated screen. Do I have heated mirrors in my truck? The electrical library indicates that the heated mirrors are also powered by the relay that turns on the rear window heater, for what it's worth.

 

Probably, but I don’t have any experience with a 99. You could maybe peek behind the mirror and see the wires. They connect at the lower inboard corner I think.

Or just try it and see, they come on with the rear defrost as you said. Pretty useful really.

 

I have them in my daily driver and love them, just have not had the occasion to arise to see if they are working on my D2, I’ll check for the wires too. Thanks!