Ok I'll look under the hood in the morning

 

Hope you find the problem, does seem odd it quit being so new. I got a new truck a few weeks ago. Haven`t hooked it to a trailer yet. Any chance Ford put a constant hot in the 7 pin?

 

I went and checked the fuses this morning under hood. Everything looked good. I used the jumper cables to hook to trailer and other to truck. Did nothing. Trailer lights still will not come on. I was on my way to work so i did not crawl under it to look for a ground so I will this afternoon. This is just plain WEIRD.

 

Since it's a fairly new truck I would expect you have manual? If it's like most F-250/350's, your fuse block is on the drivers side back and has fuses specifically for the towing pkg.

If you have a short, that fuse will blow. If it's and "open" or poor ground, the fuses will be good but generally you will see little or no lights.

I would also check your connections at the plugs.

I have to clean my 7 pin regularly to ensure good contact. The last trip, my brake contact and left turn signal contact needed cleaning.

I carefully clean with a fine file, careful to not touch two contacts to potentially blow a fuse (on truck side). I also use a quick shot of wd-40 to help ensure contact.

Since both 4 and 7 pin aren't working, probably a fuse under the hood.

Use a vom to verify if necessary.

 

get a volt meter and check the pins in the connector. with the truck on, use the voltage setting to check the 12v pin. with the truck off, put the meter in ohms and check the ground pin .

I sometimes have to clean surface corrosion of my pin connectors ....the multi meter test will tell you if you have connectivity thru the pins.

 

I would be willing to bet that its just a fuse, My truck (6.4L not 6.7) has a relay for trailer lights but then it also has a fuse and both relays were good but the fuse had blown. I would read through your manual and the fuse box that is under the hood. Check all of the fuses that are for trailer lights.

 

Seems like all the important fuses for trailer towing on my 6.4 are located in a fuse block just under the vacuum pump on the drivers side fenderwall. Have to remove the pump to access the block, and the lid on mine is tricky to get open and the put the lid back. Not sure about the 6.7, but a glance thru the manual should get all the info needed as to which fuses go to which lights/brakes. Seems odd, tho, that nothing works--I have only had brakes or running lights blow a fuse, not all of them.
Joe

 

I have almost the exact same problem. I have a '11 F-250 Gasser, and both the 7 pin and flat 4 don't completely work anymore. I have no power for running lights. Brakes, and turn signals work fine. But no runners. I checked fuses and they were fine. But no voltage on my volt meter. Its like a pin has pulled out of a plug somewhere in the line, or just completely broken off. Its driving me crazy. I've looked at the grounds and pinned it for ohms, and its a complete open line. Not just a bad ground with super high resistance. Time to keep hunting.

 

just to update everyone. I did everything you guys said and nothing. Even underneath the truck nothing looks out of the ordinary. Could not follow any grounds due to all the wires being bundled up from ford.
I am just going to take it to Ford and let them handle it. This still just has me baffled. Thank you to everyone who took time out to reply to this. I greatly appreciate you guys.

Stay tuned.

 

Including this connection? Not sure if they use salt in your part of the world but this has become a key spot for issues.

You won't be looking for a ground or bare wire, but an "open" which isn't allowing a ground to make proper contact.

Let us know what you find. Thx.

 

yes sir we have had salt for sure. I will send it and see what they find out at this point. I have a 1pm appointment with my truck. Let them figure it out at this point.

Cant wait to see the culprit.

 

Ok here is the result.

After going to my dealer they found it was a fuse under the hood that had blown. It was the fuse for the running lights only on a trailer. I thought they all were fine but in my defense I have never seen any fuses like this. They went and got one and installed it....waaah lah good as new. They can't explain why it happened but I hope to figure it out. That or hopefully this is a one time thing.

Here is a pic of the fuse for everyone to see. Thanks again for everyones help.

 

Boy, not a cheap fuse. This is a long ways from everything not working to just one fuse repairing the issue.

Like many others also said earlier, get a vom and test to get accurate data.

Glad you got it fixed but it's hard to help when the info coming to us is sketchy at best.

 

Glad you said that. I was wrong about what was and wasn't working. I couldn't see before but today when I was takin a trailer with me to ford place, I noticed the brake lights and turn signals worked but no running lights in any of the lights. The fuse fixed all that

 

Stop and turns are also a separate fuses R and L for the trailer lights!!