these are the flat prong plugs, right? sometimes one of the prongs gets bent and doesn't connect properly.. sounds like the trailer side prong is squished a little and maybe the truck side too.

I've had to bend them back into shape on a couple trailers.

 

I have a Trailer Brake Controller Test box (Simulator). As you know the TBC won’t give out an output under a certain speed but the manual slide will bypass any of the trucks inputs and apply full current.

May I suggest that with the trailer plugged in, you measure the current before and after the truck’s plug while having the manual slide over in different positions and start wiggling the trailer’s plug? This will tell you if you have a problem before or after the plug? As you stated that an intermittent problem is going to be hard to find, but you might get lucky. Also I don’t know that when using the slide if the TBC monitors the system for faults?

FYI:<O</O
The voltage and current output (waveforms) from the TBC is different then directly from the trailer’s battery. Not to confuse anyone but a digital meter has a sample rate and it is usually setup for 60 cycles (RMS) on the AC scale and usually the same sample rate for when it is measuring DC. This is one reason why you can’t expect the dealer to have a $300 test box and know how to use it.

 

Yes, but the ones I've replaced seem fine. I'm thinking they were to thin of prongs (or the female end was spread apart) and weren't making a good contact. All I can think of.

 

So here is the question, do you get the "wiring fault on trailer" message on any other trailers? I was inclined to blame the truck but when I hooked up my car hauler/utility trailer it worked great. Took me a while but I finally found a crappy connection at one axle.

 

Long time lurker, my first post.

I had a similar problem, and completely lost my trailer brakes on the run from Durango to Sliverton Colorado, towing a 2011 5er at about 10,000#. We made it to Steamboat Springs, and the local Ford dealer (Steamboat Motors), checked both camper and F250.

They found a faulty TBC Module and replaced it under Warranty. Many thanks to them since I am from WV. You may want to have a Dealer run the test on the TBC, hopefully you are still under warranty.

 

Wow! Great first post and welcome to posting at FTE

 

Thanks Arniet, I have the extended warranty on my Truck so I can certainly ask. When your dealer checked both the trailer and truck was the wiring fault message active? You reference the TBC module is this the correct term for the brake controller or is this an electronic support module for the EBC?

Thanks

 

TBC = Trailer Brake Controller

 

When a dealership replaced my trailer brake controller:

By the invoice they retrieved codes C2806, C2807. Ran Pinpoint Test C1-C5 Faulty Module.

Installed BC3Z 2C006 C : Module - Trailer Brake B

I hope this helps.

 

Thanks, It sounds like your fault was active at the time of dealer service. Mine is intermittent and I can reset it most of the time by shutting everything down, unplugging and plugging back in. Tough to diagnose if not active..but I will talk with my dealer and pass on the information you provided.

 

Update on possible TBC issue..Well as always seems to be the case, the trailer was at fault for the violent pulsating issue with my 5th wheels electric brakes.

After several replacements of wires including the 7 way length on trailer and a redo of all trailer wiring connections, I found a short on the positive brake wire feed on the last trailer break (the 4th break) inside of the axle. Keep in mind this is a 5th wheel trailer that is less than one year old with under 1000 miles on it.

LESSON...Never underestimate the trailers wiring regardless of trailers age.. the wire must have worn through on the rough inside of the axle, it was also slightly burnt so I think its the smoking gun!

I did haul the trailer after the repair for 10 plus miles with the trailer gain on 10 and exercised the brakes very hard with no issues..Thanks for all the advice.

 

Glad to hear you got it working. And thanks for the update.

 

Just qued in today.
Reading the OP "a pulsating on and off issue with the trailers brakes". Exact same issue I had in past. Went through a mess of "truck at fault" issues and resorting to RV CW and wasted $$ and time. Exhausted and turned to trailer.
Pulsating brakes = trailer wiring fault. My wife, the best mechanic I know said always check the problem area first. Hence pulsating brakes. That is where I found shorted wires from poor mfr. install.
Glad you got her fixed

 

Before you call the problem solved, you should check to see if there are any codes in the TBC on the truck. These codes do not appear directly from the ECM, you must go down to the TBC to retrieve those codes. I replaced the axles on my 5th wheel, and one of the magnet wires rubbed on the drum causing an occasional short. Found the problem repaired, but still did not have full braking. After digging deep found a code in the TBC, and that finished the repair.