Switches and armrest plate??
The heated mirrors on the '02 are part of the rear window defroster circuit, and switched on with the RWD switch in the heater/ac control panel.

I know because I ordered my truck with heated mirrors, but no RWD. Showed up without either. Dealer had to install the mirrors for free (actually, I paid the option charge for the heated mirrors when I ordered). Wiring was present, but heater/ac head unit had to be swapped out for one with the RWD switch.