I JUST went thru this only a month ago. It is the contact in the rear slider. Needs a new window. Mine worked whenever it wanted to from new until it finally gave up the ghost. ...and the door mirror defrost is on the same circut and wont work if the circut isnt complete. FoMoCo paid 80% (I have the extended warranty, but the extended doesnt cover the rear window for some ******** reason). Go to the "Exploding rear window" thread, contact Crystal (or Brittany sometimes fills in), she'll help you out. FoMOCo knows this is a bad part and they are doing the right thing by helping out rather than stick us with the whole bill (if you're out of original warranty). E.