Just dropped my truck off for the first time. She's got 28k on her. Rear and tow mirror defrost stopped working a couple weeks ago. Did a couple searches on here and found it's a common problem for 2010-2013 F150s TSB # ASI-32259. Thanks all for posting. Showed up to the dealer with the TSB and all went smooth so far. Now getting a Ram Hemi for a loaner...can't wait...