I have a 2011 F250 Lariat which includes the Electric Brake Module and towing package with the 6.7 Diesel. I am having issues with my 2014 5th Wheel 's electric brakes. The issue involves getting a "Trailer wiring fault" alarm on my trucks display and loosing control of the 4 wheel electric brakes on the trailer at random times (all lights on the trailer continue to work). I recently hauled the trailer 400 miles with no issues and then 5 minutes from home the Trailer wiring fault alarm came on and the breaks were completely gone on the trailer.

In some instances the loss turns into a pulsating on and off issue with the trailers brakes which causes havoc with the trucks brakes as I believe the trucks anti sway brake control kicks in. This makes it nearly impossible to stop the entire rig(14000 lbs). If Im quick and I drop the gain on the trailers brakes to zero the trucks brakes then do there job properly but no trailer brakes obviously. Once I get the trailer to stop and get to a safe location I have been able to get them to work again by shutting the truck off, power down the vehicle (i.e. wait for 2 minutes after the doors have been opened and shut) remove and reinstall the 7 way trailer wire into the truck and the breaks will work again. This hasn't been a 100% fix but most times has worked to regain the trailers brakes.

I have had this new 5th wheels trailer wiring checked (all ok including the emergency release breaks) and also towed the vehicle with another 2011 F350 and had no issues with the trailers brakes (albeit a shorter distance). Because of this I have assumed the truck is to blame. I have replaced the trucks female 7 way trailer harness from the bumper connection back with no luck(which incidentally looked great inside the gasketted connection considering I live in Western NY where the winter salt is abundant.

My next thought is that the EBC module which is built into the dash could be going bad. The issue seems to slightly correlate to a heavy breaking load (i.e. high current demand from the trailers 4 electric brakes). Because this is an intermittent issue I'm sure my dealer will say unless they aren't working at the time of service there is nothing they can do.

Anyone have any ideas?
Thanks

 

water getting into the trucks plug seems to be the cause of most "trailer wiring fault" or "trailer disconnected". From the factory mine came with a very healthy dose of some type of lubrication that is intended to keep the moisture out of the connections. I had a similar issue with my 2008, they replaced the truck plug and it also had the lube, which I didn't notice in the original plug.

Hopefully it will be that simple, add some dielectric grease??

Leon

 

The times I had the "Trailer Wiring Fault" message come on it was simply a connection issue.

Disconnected and reconnected and made sure it was tight and no more issue.

So, if it's not in the plug then maybe in the wiring. Is your trailer plug in on the truck the oem one or have you mounted an aftermarket one in the bed?

 

The 7 way is the OEM product which I replaced with the Female OEM product and that did not fix the issue. For all instances of "Trailer Wiring Fault" it has been clear roads with no rain involved so its not a water on the connection issue. I am tempted to replaced the trailers 7 way to see if that makes a difference but as I noted I did not have the issue using a friends 2011 F350 6.7 truck pulling the trailer.

Considering it seems to happen under a heavy breaking load, I'm still leaning towards the EBC..The electric trailer breaks want to pull 12.5 amps under full breaking.

 

Every time I have run into this situation, it has been the trailer. I've seen brand new 7 way pigtails fail. It's so frustrating. Check the grounds first.

 

I am going to clean and remount the ground on the right rear truck rail and coat it with dielectric grease. The trailers ground looks great because its new..The 7 way from the trailer fits awkwardly/loosely into the trucks so I bought a new one of a different make but it seems to fit awkward as well. I may replace the end only of the trailers 7 way with one that seems to fit better. I'm hoping some one else has had a similar experience that can help.

As always, if it wasn't intermittent it would be much easier to figure out. Then again a 2015 F250 6.7 purchase would eliminate the truck as the cause!

 

Not and expert. Sorry I was typing when others already posted.

I had the same issue on my 2008 as and since I brought it to the dealer without my trailer and the fault on, they believed it was a problem with the truck and verified that it was the conductive road dirt in the back of the connector. They had changed a few of them.

The TBC monitors the current going through the Blue wire to detect problems. A “Trailer Wiring Fault” is usually caused by too much current and a “Trailer Disconnect” is usually caused by abnormal intermittent currents going though the blue wire (open wire, bad connection).

The TBC also monitors itself and if it has a problem it can display a “TBC Fault”. Remember that a bad ground connection will add resistants to the circuit, if you had a ground problem the other circuits like the lights would be effected because of the common ground (One ground wire in the plug).

Since you posted a “Trailer Wiring Fault”, I would start by looking at the back of the connector for dirt that is causing leakage current that tracks to ground from the blue wire, this will add to the brake current and this will cause an over current. The TBC also has some current limiting protection that why a fuse usually won’t blow. It is my guess, since voltage is proportional to current (ohms Law) when you reduce your gain; you are reducing the output voltage from the TBC and not enough for current to track to ground.

Good Luck and please keep us posted.

P.S.
How do you know that it was pulling 12.5 amps and where are you taking the reading?

 

how did the plug fit on the friends truck where u didn't have problems?

 

Almost always it is a ground or a truck/trailer 7 pin connection problem.

I would start at the truck connection and take it apart and inspect, clean and tighten all the connections.

 

I've had it with both the 08 and the new 14. Both times it was the trailer. Reconnected wires on the rear axle and corrected it. Lot's of others say it is in the plug.

 

Thanks for all of the comments.

The connector on the truck (male) which is hardwired looks good at the front and back, the female connection which is mounted to the hitch was replaced and is new even though it actually looked great on the inside (filled nicely with a lubricant from the factory with no noticeable corrosion -light clear blue grease). I redid the ground last night on the truck (cleaned bolt, truck frame rail and threaded hole as well as the grounding clip on the front and back side, applied never seize to the bolt and applied dielectric to the grounding clips face and back side). Brakes still work in driveway but didn't road test yet.

As for how the 7 way fit in my buddy's truck it was no different. I did notice that the 7 way trailers male connection has a short L/D ratio which means it can actually pivot in the truck connection should it be jarred aggressively. I checked my other trailers 7 ways and they are much longer over the OD length which makes them more snug in my truck connection. I am going to cut the end of the trailers molded 7 way male plug off and put on a fresh end with a longer L/D ratio.

As for the current measurement I am going by what the trailers brakes want when the emergency pin is pulled which measures out to aprox. 12.5 amps (3.125 X 4), this was measured at the trailers emergency switch with an RMS clip on meter. While this doesn't necessarily correlate to what the truck is actually providing under breaking it does tell me what the breaks want under full load. Of course the trailers battery system would provide the current under a disconnect condition to the brakes.

 

L/D ratio?

 

I can't get lift to drag ratio out of my head to figure out what he means for L/D ratio either. Sorry, can you explain what you meant?

 

Sorry L/D - Length over Diameter. The OD-Outside diameter of the 7 way on my camper plug measures 1-5/8" with a length of 1-1/4" with the exception being at the "tang" which opens up the OD to 1-3/4" by 1-3/4" length (this is the tang on the top of all 7 way plugs). My trailers 1-1/4" plug length is rather short for a typical 7 way. My other trailers plug length at the same 1-5/8" diameter is 1-3/4" long which amounts to 1/2" more "plug". Think of it as a 2" diameter hole that measures 2" long and you are putting something with a 2" OD but only 1" long in the hole. This won't be as stiff if the entire length of the hole was filled with a 2" OD by 2" long plug.

This is only a theory and it falls apart when you consider I used my buddies identical truck and it worked fine with my trailer (again for a shorter travel distance though). I'm just trying all the easiest fixes first..

 

I've replaced perfectly good looking (at least to my stupid eye) plugs before with identical plugs and suddenly things started working. It's not a bad strategy to start there as you stated. It will certainly rule that out and you can move on to another area.