Most heated mirrors turn on along with the rear window defrost switch.
The 'defroster' switch will initiate the defrost on all areas Subaru has equipped w/ heated mirrors/ windshields.
The heated mirrors are activated with the rear window defroster - according to the Owners Manual.See "Related Questions" below for more
Usually they come on when you press the button for the heated rear window.
I believe when you turn on the rear window defroster the heated mirrors also turn on
According to the 2004 Ford F-250 Owner Guide the heated outside mirrors are heated automatically , there is no switch to turn on
Push the rear window defrost button , located with your heater controls , that also heats your exterior mirrors
Take off the cover on the inside of the cab that houses the bolts/nuts for removing both mirrors. See if there is already factory wiring in that compartment. My 2000 Silverado has factory heated mirrors but, it is a delux eddition that also came with the 4th door and heated seats that a lot of 2000's did not. If it doesn't already have the factory wiring, it depends how savy you are with electrical work. It can be done, just won't be overly easy. The first answer of just selling the truck was a little immature. Jon
The heated mirrors on my 1999 Subaru Forester are controlled by the rear window defogger switch which is located in the dashboard console above the heater controls and to the right of the hazard flasher switch. I'm not sure whether the heated mirrors were optional on the early Foresters or not. Anyway, the heated mirrors (and the rear window defogger) will stay on for about 15 minutes when you press the switch. You can turn them off before then if everything has defogged already. Also, the switch only works with the ignition on.
They should turn on when you turn on the rear window defrost.
Everywhere! Look in the rearview mirror and both side mirrors, then turn your head and look to the left and right and behind to get the blind spots from the mirrors.
It is integrated to the rear window defrost. When the one button is engaged, all three elements become energized.