At the rear underside of my truck, just in front of the bumper I have a bundle of wires that runs inside one of those black tubular covers. I assume most of the wires are for brake lights and such, but there is one wire that you can see in the picture is sticking out a few inches, and not connected to anything. About a foot farther towards the passenger side is a wire grounded to the body that isnt connected to anything either. I don't know if the wires should be connected as a ground. The guy that had the truck before me had the wire that appears to be a ground, tied around the spare tire mount, so it may be something he added on there just to hold the mount from swinging, so I was hoping someone out there knew what the wire coming out of that rear bundle is for. Any takers?

 

connect it together
but first take a test light and hook it to the wire comiong from the wire harness and see if it lights up meaning its a power wire
if it dont that probley means ground
could have got stuck on a trail run or something

 

Does your truck have both factory license plate lights, or did someone switch them out for aftermarket ones.

 

It's the stock license plate lights, I'm not sure if only one or both work though. Another thing is, the wire from the harness and the wire that's grounded are different gauges. I'm going to stick a test light on it today. I just noticed it when I was under the truck taking pictures of the exhaust, so I just snapped a picture.

Does anyone else see this wire coming out under their truck?

 

I have a whole plug hanging down around the same place (near the tank) it comes out the black cover to.. I always just assumed it was somthing extra on the harness for double tanks or somthing..

 

Well I have dual tanks. And the rear one doesnt work. But I would think the ground for the pump would be at the front of the tank, I believe that's where the wires from the fuel pump run.

 

Hmm im not really sure.. the plug hanging down on mine is a little 2 prong connector but i dont see anything to plug it into..

 

Theres a few plugs near that wire, but mine are all plugged in. Maybe yours is a plug for trailer lights?

 

i say if it aint broke, dont fix it... if all the lights work, dont worry about it. Ford uses the same wire harness for a few different truck, i could just be an unused wire on your truck. If it was me, id put wire nuts on them and zip tie them up.