installed new unit in my 2003 f150. when i rmoved the factory unit there was two plugs. one which match the aftermarket wire harness and one with a single gray/ black wire. with no where for this wire could this be my problem and what can i do to fix it. everything works exept rear speakers
that sounds like the negitive rear, my guess is that etheir for whatever reason your HU wire colors are differ or your wire is missing, like he said check out a diagram and look where the neg is suposed to be on your HU harness. if its missing etheir look for a new one or if you know a bit on wireing get a pin for the harness(radio shack) and sodder it up to your neg and plug it in, just make sure absolutly that that is what it should be, im sure you can find a diagram online somewhere