This heating pad fits pretty well in the swivel cup on the mirro…

This heating pad fits pretty well in the swivel cup on the mirror backing plate, and after testing it in my deep freezer, it works well enough for me. Obviously, they don't heat the WHOLE mirror, but it's enough to make them useable. Fortunately, I added wiring for mirror heaters to the door harnesses last year when I had them out, so connecting them will be easy. And like the LEDs, breaking the glass won't hurt the heating pads. I'm using 3M Super77 spray adhesive on the pads to attach them to the plates.

Wiring these is relatively easy in Broncos since most of them already have a rear defrost timer in the dash. But it's not much harder in trucks without that, and a timer isn't really necessary. These can run continuously without damaging themselves or the mirrors, so a simple switch is good enough (I recommend one with a pilot light). And they draw very little current, so it's safe to add them to an ignition-switched circuit so they go off with the key.

UPDATE 3/15/15:
I built & installed heated signal mirrors for a local Bronco enthusiast last year, and he reported after the recent blizzard that the heaters WORKED.

UPDATE 12/15/21:
I still haven't wired my heaters up, but I ripped a mirror off off-roading today so I may wire up at least that one when I fix it.

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Owner caption April 2014 · Photo 5094 of 6546