I have a question about installing a new head unit into a 2003 Ford F150 Supercrew FX4. I bought a new Sony head unit, wire harness and installation kit. The problem I am having is that when I remove the factory unit there are two wire harnesses attached to the back of the stock unit. The wire harness I bought for installing the new unit only came with one harness.basically it would not touch the other wiring harness on the back...

Does anyone know what this other harness is and what would happen if I didn't connect it? I had a buddy that installed a new stereo in his explorer and it was a 4x4 and he said the 4x4 switch didn't work after installing it. Now I don't know if he used a wire harness or not, or if this was even the issue for it not working, but I do know that sometimes manufacturers will run wires through the stereo for whatever reason thereby when the stereo is replaced certain things do not work. Does anyone know if this is the case or is it alright not to use that other harness and leave it "hanging and not plugged in"?

Thanks for your help - I really don't want to mess anything up just because it is time for a new head unit.

 

My 98 sounds like the same setup. the first harness I got only had the one end, had to return it to get a proper 2 end one. though, I always thought that 99+ only had the one ended harness...

 

I have a 2002 and it only used a single plug for the sony i have. It also has a six cd changer in the center console,,they dont make a harness to control the 6 cd changer.