Hi All,


New member here and I hate to introduce myself with a question but I have one anyway.


A week ago last Saturday I bought a 2006 F250 Lariat Crew Cab with the 6.0 and 4WD. The truck is really clean and only has 68,000 miles on it. Here's my question: I needed to tow a boat today and I discovered I have no power, at all, at the trailer light plug receptacle. Nothing at the 7-pin nor the flat-4. I looked through the manual and checked every fuse that had the word trailer associated with it and I can also feel the turn signal relays clicking with the flashers on.


Am I missing something really simple or do I just need to follow the wire harness from the back and look for something that is not connected? It seems kind of weird for it to be just....dead.


I really need to get this boat moved so I am looking for any tips anyone can offer.


Thanks, I really like this site so far.
Shawn

 

Pull a diagram on the wire harness. They are all pretty standard. Once you find a diagram use a meter and start testing the wires for resistance, can also check for voltage with the truck running. Pretty sure the 4 pin harness is spliced off the 7 pins though.

 

Here are some exterior light wiring diagrams....hope it helps





2006 F250 Exterior Lights 1





2006 F250 Exterior Lights 2





2006 F250 Exterior Lights 3

 

These wiring diagrams are great! Do they also apply to a 99 7.3 SD? Do I really have to start by pulling apart the main junction box and removing the dash?

 

I would start at rear and do checks towards front of truck before do any major component removal.

here are the 1999 wiring diagrams





1999 SD exterior lights 1





1999 SD exterior lights 2

 

Dont forget to check the relays under hood.

 

relays under the hood and the fuse block in the cab.


Pull the 7 pin connector apart and check those wires and connections too.

 

And if you have the dual battery, the extra one may feed the trailer portion, it did on my E-350 and I had low voltage.

 

My 01 came with a fuse and relay kit in the glovebox for trailer lights. Have they been installed in the power distribution box under the hood?

 

Thanks everyone for the responses.


So the next morning I found a different round-7 to flat-4 adapter with the small red indicator lights that I had laying around the garage. Plugged it in and all the lights lit at the proper time. So I went back and re-checked the trailer and found a spot where the trailer wire insulation had worn through. I spliced in a new section of wire and all was fine. I feel kinda stupid that I missed it.


Thanks again for the suggestions.

 

It's the simple things that'll get us every time.

Thanks for letting us know what the problem was.

 

The LED trailer light tester worked on my van, even though there wasn't enough voltage to operate the trailer lights.
I built a tester that has incandescent lamps, for the trailer running lights, to show what is really going on.
I made a mount to attach it to my tripod.
I plug it in and stand it beside the truck, so I can see it in the mirror.

 

Where can I find the schematics on this site?
I need to see the truck backup light circuit.

 

most trailers don't have a set of backup lights.


etrailer.com will have a diagram

 

I'm working on the truck backup circuit, not the trailer.