Alert: "Trailer Wiring Fault" - Diesel Forum

Incorrigible · 02-14-2013, 05:42 PM

This just started today - upon startup the info screen on dash says "trailer wiring fault". Press the "OK" and it goes away and never returns until startup again. I took to dealership and they said it was moisture in the aftermarket 5th wheel wiring and it may also have corrupted the trailer module. I disconnected all wires from the factory trailer harness and still get the fault indicating the module may be bad - or there is a short somewhere else in the factory harness. I know when I get to the dealer tomorrow they are going to say that the module is bad and it was MY 5th wheel harness that caused the issue and the module is on my tab and not warranteed.

I know flat rate pays a whole lot more than warranty rate. I know Magnuson-Moss says they have to prove my harness fried their module but it is my word against theirs. They are a local Ford dealer and the nearest next one is not convenient.

I bought the 2011 truck used w $11k on it and today it has 17k.

Any thoughts/comments?

**HoustonRider** · 02-14-2013, 06:00 PM

I would assume moisture is part of the deal in a trailer wiring harness, they arent water proof and if you submersed it (not the 5th wheel plug in the bed) backing a boat, the OEM plugs would be "moist" as well.

I would bring that logic to em and like you said, proof is on them to a point. I can see em going that route and leaving you with all the pieces, we have some Ford Reps that frequent here if you run into a roadblock.

It is kinda coincidental you have an aftermarket harness and a trailer wiring fault problem. I would see how they narrow it down.

Incorrigible · 02-14-2013, 06:45 PM

Thanks HR for taking the time to reply. I'll update tomorrow.

MPD56 · 02-15-2013, 03:21 AM

I had a similar problem with my 2008 caused by road salt getting in the back of the 7 pin connector, the Ford Tech sprayed the OEM connector with contact spray, blew it dry and then he packed it with silicone till they got a new one in and replace it. If I remember right, they had a couple on order and had replaced a few already. I know that he knew and went right to the problem spot first thing. I know in the 2008 owners manual (I don’t have my 2013 manual with me) it states that these messages are to let you know there might be a problem, I can’t believe that a module can be damaged by a fault that it is intended to diagnose (detect), The module has built in protection.
If your after market plug was the problem then I can see you paying the bill for their diagnostics, but not the module. Trailers are known to have many wiring problems and their module has to be made to withstand them to detect them. Even in the manual it states shorts to ground and shorts to voltage.
So, my way of thinking is that if your plug caused the problem then why didn’t the fault clear when it was disconnected? Because the module is defective or the truck’s OEM wiring and should be covered under warranty.

CUT & PASTE from 2008 Owners Manual
WIRING FAULT ON TRAILER: The TBC is capable of determining
certain faults in the vehicle wiring and trailer wiring/brake system. These
faults do not mean there is anything wrong with the TBC. This message
is displayed when one of the following faults has occurred:
• Short circuit on the electric brake output wire: If the TRAILER
FAULT message is displayed with no trailer connected, the problem is
with the vehicle wiring from the TBC to the 7–pin connector in the
bumper. If the message is only displayed with a trailer connected, the
problem is related to the trailer wiring; consult your trailer dealer for
assistance. This can be a short to ground (i.e., chaffed wire) or a short
to voltage (i.e., pulled pin on trailer emergency break-away battery) or
trailer brakes drawing too much current.
Note: Your TBC can be diagnosed by your authorized dealer to
determine exactly which trailer fault has occurred; however, if the fault
is with the trailer this diagnosis is not covered under your Ford
warranty.

Incorrigible · 02-15-2013, 06:26 AM

Thanks MPD!
I appreciate the education and this is a GREAT site.

PerryB · 02-15-2013, 06:45 AM

Is your fifth wheel harness plugged into the Ford provided connectors or is it cut and splice (P.S. Early 11's didn't have aux. 7-way connectors under the truck) ? If is plugged in then obviously you could un-hook it and see what happens. If its spliced in, I'd take the socket apart/off and see if the message goes away. You may just have an errant strand of wire causing your problem. Also, check all your fuses. Whatever caused the initial problem may have blown the fuse powering your electric brakes. Trailer/wiring fault messages are triggered by the brake circuit.

winter traveler · 02-15-2013, 08:14 AM

I dont buy the moisture. First time in a heavy rain would short everything out and those harnesses do not because they are built to withstand that. I would suspect something wrong with the harness install. I have had three trucks, all with a second receptical in the bed and have never had the problem you described.

MPD56 · 02-15-2013, 12:02 PM

Incorrigible:
I’m only guessing because it is hard to troubleshoot over the internet. If you own two Ski-doos, then you know about road salt and snow machine trailer wiring problems. I’m only saying that if any trailer brake controller couldn’t survive back yard wiring, then there would be a lot more posts then yours.
On page 249 of my 2013 owner’s manual it states among other things that if the module is having a problem, it should display a “TBC FAULT”.
Please keep us updated.

PerryB:
Thanks for the information, I only have 100 miles on my new F350 and didn’t know that there might be an Aux 7 pin connector under the truck. One reason I never put a plug inside my trucks box, is that I didn’t want to cut into factory wiring.

scjmc · 02-16-2013, 11:01 PM

My boat trailer has some serious wiring faults of its own. I have never gotten a message about it.... Most lights just don't work.

Incorrigible · 02-17-2013, 10:15 AM

Thanks for all the suggestions. Now that I'm still getting the code after removing the aftermarket harness I have to make a decision whether to bring it back to original (local) dealership and chance them telling me my harness ruined their module thus I'm paying for the repair, or travel to a further dealership that has no knowledge of harness.

When I made the appointment for next week w original dealer I asked if this sounds like a warranty repair since I'm still getting the code. The service advisor said "Well, you know your aftermarket harness was wet (Duh! its under the truck!) and it may have shorted our module out - I guess we will have to see."

How can a dealer prove my harness caused the issue? I wonder where the burden of proof lies? I have a feeling the dealer is salivating, waiting to stick it to me. If warranty labor rates were the same as book rate I don't think this would even be an issue.

MPD56 · 02-17-2013, 03:10 PM

Welcome to the Ford shuffle, There is no such thing as burden of proof, the dealer is telling you that the aftermarket wiring caused your problem and it doesn’t matter what you say, they want you to pay for the repairs. Bringing it to another dealer will probably end in the same result because the last dealer has probably entered your visit into the Ford’s data base and it is now on record.
In my opinion!! “Will have to see” means that they haven’t called ford and or they didn’t really confirm the cause of the problem or what needs to be replaced or repaired. The dealer can’t just repair things for free, that is why I’m guessing they put the special note in the manual, in your case you sliced into a factory wire harness and the Dealer just stopped there with their diagnosis. If they did, I would assume they would’ve given you a total price of repair.
I could be wrong and just my way of thinking, I really don’t know all the facts.
I was hoping a Ford tech member would’ve join in and correct me, but the TBC has to have over current and short circuit protection and it should be able to detect and protect it’s self (I know the 2008’s do) If it was my truck. I would’ve had no problem paying for the diagnosis (which you didn’t say you were charged), if it was me that caused the fault with an aftermarket connector and the TBC fault didn’t clear after I removed my problem, I would assume it’s a Ford Warranty problem and therefore wouldn’t be charged. I connect a lot of trailers to my truck with crap wiring and if my Ford TBC was damaged, I wouldn’t think I'd have to pay?

PerryB makes a good point, I don’t know if a blown fuse in the trailer circuit will cause the TBC to cause a fault message, I only assume it would. You haven’t said that you checked the fuses, it might be that simple.

I don’t like giving advice over the internet, but if you confirm that the dealer is going to charge you for a module, I would PM Crystal, a Ford Customer Service Representative that is a member of this forum and always helpful and I wish Ford Canada would learn buy her example of good service.

Sorry about the length…Good Luck

FordCustomerService · 02-18-2013, 01:04 PM

Quote:

Originally Posted by Incorrigible

This just started today - upon startup the info screen on dash says "trailer wiring fault". Press the "OK" and it goes away and never returns until startup again. I took to dealership and they said it was moisture in the aftermarket 5th wheel wiring and it may also have corrupted the trailer module. I disconnected all wires from the factory trailer harness and still get the fault indicating the module may be bad - or there is a short somewhere else in the factory harness. I know when I get to the dealer tomorrow they are going to say that the module is bad and it was MY 5th wheel harness that caused the issue and the module is on my tab and not warranteed...

Hi Incorrigible,

I'm happy to look into this for you and see how I can assist. Send me a PM with your VIN, dealer, mileage, daytime phone number, and full name; I'll look into some options.

Quote:

Originally Posted by HoustonRider

....I can see em going that route and leaving you with all the pieces, we have some Ford Reps that frequent here if you run into a roadblock...

Quote:

Originally Posted by MPD56

...I don’t like giving advice over the internet, but if you confirm that the dealer is going to charge you for a module, I would PM Crystal, a Ford Customer Service Representative that is a member of this forum and always helpful and I wish Ford Canada would learn buy her example of good service...

Thanks for the shout-outs, HoustonRider and MPD56!

Crystal

Incorrigible · 02-19-2013, 06:09 PM

Update - the dealer said the module is bad and they would warranty it. Of course they had to have the last word and say that my harness caused the problem...
Parts on order.
Thank you Crystal and all else for their suggestions.

FordCustomerService · 02-20-2013, 10:08 AM

Quote:

Originally Posted by Incorrigible

Update - the dealer said the module is bad and they would warranty it. Of course they had to have the last word and say that my harness caused the problem...
Parts on order.
Thank you Crystal and all else for their suggestions.

Thanks for updating us, Incorrigible. I'm glad to hear that things are moving in the right direction.

Crystal