F350 Trailer wiring fault when towing my XLR

[nguyenbio]

Okay here it goes. I have a 2015 F350 towing a 2016 XLR. For over a year, everything was fine. About two months ago, I slowly started getting a "Trailer wiring fault" message when starting off a trip and then sporadically getting "trailer disconnected" and "trailer connected going on and off, even though the trailer is connected the entire time. During this time, all my lights work and brakes work perfectly.

Lately, when I take off at the beginning of my trip, the wiring fault message loose us after a few seconds at idle speeds, all lights work but no brakes. After a few seconds longer my brakes begin to work. During my driving at highway speeds I always check my brakes when the message sporadically pops up and have never lost my brakes at highways speeds. When I get to my destination and slow down, the wiring fault pops up again, I loose my brakes again at idle speeds.

I have checked and used both the bed receptacle and bumper receptacle and the same symptoms exist. I tried to go underneath and wiggle the trailer brake wires and cannot replicate the problem. I've cleaned and use dielectric grease on all connections and same results. I also double checked the j box to ensure all connections are tight. No connections had water intrusion

My next item is to test each magnet and re-run all axle brake wires to the outside of the axle. This is the result of talking to Dexter. I may redo all the brake wires period!

According to Ford, the problem is only on the trailer side if the wiring fault pops up when no trailer is connected. I guess one bad magnet will send the trailer fault message to the integrated brake controller and the truck senses that all brakes are bad. Dexter and Ford agrees it's usually the trailer and not the IBC.


Does anyone have any ideas or experience with this?? I would tow another trailer or have another person tow mine but I don't have any friends with fifth wheela!

[lincster]

nguyenbio wrote:
UPDATE!!

Before pulling off my hubs, I decided to go through and inspect every brake wire inch by inch. Wouldn't you know it, there was a tiny nick on one of the wires located on the middle axle that was rubbing on the top of the spring mount. The nick exposed enough wire to catch the corner of the mount, which then sporadically sent the wiring fault message due to it being grounded out. I repaired that wire and went ahead and checked the inner axle wires. Wouldn't you know it, the third axle also had some bare wire that was exposed in the axle. Apparently, the insulation had worn off bouncing inside the axle. I went ahead and pulled all axle wires, split loomed them, and mounted them on the upper rear part of each axle with large zip ties. This was advice given by members on here and by Dexter themselves. I also split loomed and secures all other brake wires, eliminating any chance of having this specific problem occur again.

I want to say thank you to everyone on here for their advice and encouragement!

Good deal.
Usually the issue is something simple.

[Dirtclods]

(factory attached plug was the problem)-Same here!

[nguyenbio]

UPDATE!!

Before pulling off my hubs, I decided to go through and inspect every brake wire inch by inch. Wouldn't you know it, there was a tiny nick on one of the wires located on the middle axle that was rubbing on the top of the spring mount. The nick exposed enough wire to catch the corner of the mount, which then sporadically sent the wiring fault message due to it being grounded out. I repaired that wire and went ahead and checked the inner axle wires. Wouldn't you know it, the third axle also had some bare wire that was exposed in the axle. Apparently, the insulation had worn off bouncing inside the axle. I went ahead and pulled all axle wires, split loomed them, and mounted them on the upper rear part of each axle with large zip ties. This was advice given by members on here and by Dexter themselves. I also split loomed and secures all other brake wires, eliminating any chance of having this specific problem occur again.

I want to say thank you to everyone on here for their advice and encouragement!

[lincster]

Oh man.... Welding and batteries don't do well together. LOL

[nayther]

Had a similar issue with error codes, lost trailer brakes on the way home once. Very interesting as the warning/loss came as I was going down a steep hill! So connected a buddy's trailer and found it it didn't work that way so figured it was the truck. I took it to the Stealer thinking it was a truck issue under warranty, NOT! They found a blown main trailer loom fuse; so that said it was MY trailer. Found a short in the charge circuit wiring that took out the main loom fuse which apparently is what powers the onboard brake controller. Fixed short and bought a spare fuse.

PS, short was caused by ME melting a wire while welding supports for my new 6 volt batteries.........DOH!

[mogman]

I'm not familiar with your trailer, but do the brake wires run through the axle tube?
Sometimes the wires chafe inside the tube and cause intermittant shorts.

Edit... I see you already ran the wires to the outside of the tube.

[lincster]

B-rad Lee wrote:
I had a bad Integrated Trailer Brake Controller (TBC) on my 2005 F350 that was giving me a similar problems. I would try another trailer first before i started digging into the wiring... if you have access to a bumper pull trailer with electric brakes, it might help you troubleshoot a bad Trailer Brake Controller (TBC) too.

The older Fords had this issue. There was actually a TSB issued for it.
I should know, I owned a 2006.

The newer trucks don't have this same issue.
Besides, as someone else stated, they have the same issue with a Chevy.
So, like I said, nothing wrong with the truck.

[east2surf]

Literally just had this with a 2016 Silverado 3500DRW and 2018 Road Warrior 425. Turned out I had a severed brake wire in the right rear hub of the trailer. DO NOT disregard that error message, get it checked ASAP!

[nguyenbio]

tmilicia wrote:
I also have a 2015 F350 and 2016 XLR Thunderbolt. I had the same exact problem the first year I had the trailer. Pop off your trailer hubs and you'll find one of the brake wires has come out of the wire clip and rubbed itself raw on the hub. I went through all my hubs when this happened, and of course it was the last one of 6 wheels where I found the issue. The wire was pretty badly damaged, so I just installed a new magnet and all was good again. However, at the start of this season, the problem returned. I had a feeling about that one brake wire clip (last wheel on the curbside of the trailer) and sure enough, when I opened it up, the wire had come off the clip again. I probably should have just ordered some new clips, but I just zip tied that sucker to the brake arm inside and it's been fine all summer. While I had it up in the air, I ended up just opening all the hubs up for inspection and repacked the bearings too.

Did you lose your brakes sporadically at low speeds when it would show the wiring fault message??

[tmilicia]

I also have a 2015 F350 and 2016 XLR Thunderbolt. I had the same exact problem the first year I had the trailer. Pop off your trailer hubs and you'll find one of the brake wires has come out of the wire clip and rubbed itself raw on the hub. I went through all my hubs when this happened, and of course it was the last one of 6 wheels where I found the issue. The wire was pretty badly damaged, so I just installed a new magnet and all was good again. However, at the start of this season, the problem returned. I had a feeling about that one brake wire clip (last wheel on the curbside of the trailer) and sure enough, when I opened it up, the wire had come off the clip again. I probably should have just ordered some new clips, but I just zip tied that sucker to the brake arm inside and it's been fine all summer. While I had it up in the air, I ended up just opening all the hubs up for inspection and repacked the bearings too.

[kofire]

lincster wrote:
Yep, has happened to me a couple of times.
If you spend enough time, you will find the broken wire or bad connection. it is there somewhere in your brakes on your trailer.
Nothing wrong with the truck or the plugs in the truck.
100% somewhere in the trailer.

This is my experience with this exact problem. Ended up being a worn drum brake magnet and associated wiring.

[B-rad_Lee]

I had a bad Integrated Trailer Brake Controller (TBC) on my 2005 F350 that was giving me a similar problems. I would try another trailer first before i started digging into the wiring... if you have access to a bumper pull trailer with electric brakes, it might help you troubleshoot a bad Trailer Brake Controller (TBC) too.

[98silvz71]

I know this might not be your problem, but if you haven't checked it out its worth a look. With one of our many trailers, the factory attached plug was the problem. As soon as we hit a big bump or turn just right, the truck would say trailer disconnected. It would happen so fast that the lights would just flicker for a second. We buy one like this and have used it on multiple trailers. https://www.etrailer.com/Wiring/Hopkins/HM48510.html

I hope you can trace the wires if that is your problem. I can't trace mine very far. Good luck.

[Ralph_Cramden]

Crawl under and take the time to remove all the feces connectors on the brake wiring if you can get to them, and either solder / heat shrink all of them or replace with Scotchlok IDC's. Soldering is better.