"Wiring fault on trailer"

[CraigB in FL]

etting a "Wiring fault on trailer" notification on the info display of myt 2015 Ford F350 SuperDuty. The owner's manual indicates it is likely a short in the wiring of the trailer braking system. I saw some online references that suggest the magnet in the brake assembly may be worn, thus shorting out. Is there a way to confirm whether it is the magnet(s), without having to pull each wheel? Are there other checklists you run through to pinpoint the source of the short?

If I need to replace the magnet(s), does anyone know what part numbers I need or where to get them?

It's in my signature, but this is for a 2015 3582RL. I've probably put 15K miles on it since we bought it a year ago.

Thanks!

[AZ Traveler]

Craig,

It is likely a shorted wire going into the axle tube or inside the drum. It is best to start pulling drums to see what you have.

[Lee-CI]

Originally Posted by AZ Traveler

Craig,

It is likely a shorted wire going into the axle tube or inside the drum. It is best to start pulling drums to see what you have.

^^^^^ Agree with Zach 100% on this one. Just too easy for the brake wiring to get damaged back there by road debris. Good luck and let us know how you come out.

[Rondo]

Zach has your answer to your question. I would be checking both the wires going into each of the hubs and also the wires running into the axles. There have been other posts about this problem and the wires wear the coating off and short out.

[dieselguy]

I'll agree with Zack and Lee and add I've only seen a failed magnet once in years and years of staring at trailer brakes. The issue further promoted by replacing the magnet "just because" is the magnet wears on a flat surface on the inner face of the brake drum. Grooves and high/low spots form just like on a car's drum or rotor after miles and miles of use. Just replacing the magnet usually results in disappointing brake response unless you find a place to turn the brake magnet surface as well or replace the whole drum. The new magnet will be flat faced ... the surface inside the drum will grooved from use.
Each magnet pulls about 3 amps (12 amps total for 4 wheels) ... a clamp on ammeter on the blue wire in your junction box under your pinbox can confirm that or ... have someone press on the truck brake pedal while you hold a magnet near your brake drums ... it should swing wildly. The brake wire runs inside the axle tubes. There is usually a gromet on the axle behind the backing plate where the wire exits and goes inside your brake drum. I've seen a few bare wires in this area. But ... just extra info because pulling the drums would be best.

[Lee-CI]

dieselguy - I too have seen but one failed brake magnet in more years than I care to mention. On that one, the arm for the magnet had rusted through and the magnet caused enough havoc inside the drum for this o'le sailor to let loose a blue streak not fit for young ears.....
Hoping Craig just finds a bare wire that he can cut, solder spice and put heat shrink tubing over.

[BB_TX]

As a preventive measure, I gently pulled my wires out of the axle hole just enough to wrap them with several turns of electrical tape and then pushed them back in the axle to reduce the risk of the metal axle hole wearing the insulation on the wires. Then I wrapped the exposed wires to the hubs with spiral wire wrap to help protect them from road debris.

[laverdur]

I had this error and a few others, depending on what was happening at the moment. It took me a lot of troubleshooting to finally determine that the brake wires inside the axle tubes were chaffed and the conductors were shorting to the metal axle tube. Ford trucks send a health and status pulse to the trailer brakes every 4-5 seconds. If a short exists at that moment you will get a fault. The short will come and go as the axle bounces down the road so the fault is very unpredictable. Sitting still, if the wire is not shorted, the brakes test perfectly. I don't want to tell you haw many nights I lost sleep over this problem. Solution - cut the wires going into the axle. Buy a small spool of wire and put new wires on the outside of the axle tube. I went to Home Depot and bought a strip of plastic Wiremold long enough to cover the wires as they traverse the axle. A few zip ties later and you are good to go. No errors since making that fix.

[DougVelting]

Glad i came across this thread. We just had this happen to us twice over the last thousand miles. Bearings and brake pads was on the list for this winter, guess i will add checking those wires to list while im down there too. I must have spent the next 50 miles each time wondering what it could be.

[laverdur]

The thing that makes this problem hard to find it that it is intermittent and is most likely to occur when in motion and the wires are bouncing around inside the axle tubes. Over the many months I tried to find this problem, never once was it present when I was parked. For a brief moment I thought about using the old wires to pull new wires through the axle tubes and then decided against doing so because the new wires would chaff too. Good luck with yours DougVelting.

[Foldbak]

Originally Posted by laverdur

The thing that makes this problem hard to find it that it is intermittent and is most likely to occur when in motion and the wires are bouncing around inside the axle tubes. Over the many months I tried to find this problem, never once was it present when I was parked. For a brief moment I thought about using the old wires to pull new wires through the axle tubes and then decided against doing so because the new wires would chaff too. Good luck with yours DougVelting.

I was thinking the same thing. The obvious place to start is the brakes but dont rule out a chafed wire.

[DougVelting]

We are moving sites later today. hopefully next weekend i can take a look at the brake area and bearings and bang them out quickly so i can get the skirting done before it gets too cold up here in NJ.

I will most likely try and find some way to help ensure this is a one and done fix, be that running the wires a new way or something. I hate doin stuff twice