F350 Trailer Wiring Fault Message

[dfredendall]

I am getting an intermitent dash message on my 2008 F350 reading "Trailer Wiring Fault" when the trailer is connected. Twice since leaving for Alaska my trailer brake controller stops working and I also get "Trailer Disconnected"message. First time was in Utah in dry weather. Lately in Montana it has been during rain. I have checked all trailer plug connections, brake wires for solid connections and have found nothing obviously causing a short. This happened about a year ago after rainy weather, then it mysteriously corrected itself.

I repacked trailer wheel bearings and inspected all brakes prior to the trip. All looked good. I also installed new Bargman LED taillights on the bird prior to the trip. They work great, and correctly. I have heard that some truck electronics are confused by low voltage drawn by LED lights, which may lead to phantom computer messages. Anyone have any clues here? I am watching the trailer's front axle where the brake wire goes into the axle tube to cross left to right, and exits a hole in the axle tube to reach the right brake. The wires are tight to the axle "U-bolts" and may be pinched. I may need to provide space for relief of the wire. I cannot think of any other potential issues. Has anyone had experience where Ford needed to "flash" the control module to reset the brake controller function? I'd like to solve this before I get too far into the Alaska Hwy.

[campswithcritters]

Every single brake electrical problem I have ever had has been caused by the trailer electrical pigtail hooking to the truck. Have you tried electrical contact cleaner on both sides of your truck to trailer connection? Available at most auto parts stores and a quick fix in most cases, I use it once a month now and no problems for 3 years. Just a quick thing to check & cheap. You can also try WD-40 if you have some on board, not as great as proper cleaner but will get you out of a pinch.

[bigbunkhouse]

When i have gotten the same message on the fleet, it has always been the connector. Like bruce said, clean it, I add some di-electric grease and problem solved. If you just plug it in and out a few times and the message goes away it is most likely just a dirty or oxidized connector and the repeated plugging will scratch the contacts clean. The trucks are real sensitive to bad grounds, if ya want to get fancy, get a DVOM and measure resistance from trailer frame to truck frame with the plug in. it should be very low, if not bad connection. You ever follow a guy with a trailer whos lights flash with the bumps in the road? typically has a bad ground and its grounding intermittenly thru the hitch as it gets "scratched" by movement over bumps.

[dfredendall]

Good points from both of you. I did buy some contact cleaner/lubricant at Radio Shack two days ago and used it. I forgot to mention that. I used it in the parking lot after buying it and it seemed to help, but we only drove a short distance to camp. We move again today. I checked both female plug-ins and the pig tail at the plug, plus the junction box under the kingpin box. All connections were tight and dry. I agree, 99% of 12 volt electrical issues involve poor grounding. A note on contact cleaners. I have had some that ate and destroyed plastic. The one from R/S said "safe on most plastics". I tested it before shooting it in and on the plug. Checking truck ground would be a next step. I have no rust issues, but things can sure work loose. Thanks.

[Rob & Cathy]

I am getting an intermitent dash message on my 2008 F350 reading "Trailer Wiring Fault" when the trailer is connected. Twice since leaving for Alaska my trailer brake controller stops working and I also get "Trailer Disconnected"message.

It's my understanding that the truck controller monitors the brake wiring and you'll get those messages if it detects a shorted, or more likely, an open brake circuit while moving. I had a similar issue with my old TT and my '05 truck. The problem was never completely resolved but never had it again after I bought the Cardinal.

Rob

[Chief409]

I was under the 'Bird the other day and noticed the brake wires come out of the axle, with a crimp connection just before that on the left side.

[bigbunkhouse]

jeff, that is a yearly area of repair on the 7 trailers I maintain, the wires are always breaking at the crimp.

[dfredendall]

Update, When I left Glacier Park the message and alert tone was going every 10 seconds with no trailer brakes. Reinspected and found nothing obvious. Read the owners manual for the truck. (Yes, I wimped out and read the manual!) It said dealer can run diagnostic, so I hit the dealer in Whitefish, Montana. GREAT GUYS! Diagnostic said controller is fine, and had a trouble code for "direct short". Technician recommended dissecting factory 7 way plug at bumper hitch. Oh was it corroded! I have dipped it launching boats in past. $65 for new plug, and $35 for new pigtail to attach to wiring loom, and $100 for diagnosis. I decided not to pay $350 for him to install parts. With his recommendation, I cut off the old plug, terminated the wires and am using my added plug in the truck bed. I will be checking that one too. I still have issues so I have wire to bypass the pinched brake wire crossing inside the trailer axle. I will do bypass surgery today as it has rained the past 6 days of travel. When I hit a big bump in road the "trailer disconnected" message comes up, plus wiring fault. That leads me to believe axle flex is pinching wires. I hit RESET button and it is good. I hope today's surgery is successful. Won't know for sure until we roll again. I may wait to reinstall the bumper plug until I get home since I really don't need it. The technician at Ford dealer said the controller is real sensitive to excessive wiring resistance, so I may need to install it to complete a circuit. He also recommended packing it with dielectric greese to minimize water exposure. I'll keep you posted.

[dfredendall]

I was able to completely inspect and check the trailer brake wiring from connector plug to each brake with my VOM showing no shorts. The brake wires running through the axles tested fine. I solved the problem when I installed a secondary ground wire at the junction box in the hitch pin box. There was no way I was going to find the trailer chassis ground wire so I made a new one. Several hundred miles on the Alaska Highway have shown no further issues. I will install the new factory plug when I get home in August. I do not need it at this time. I will also add a secondary ground wire to the new 7-way connector. Met a guy in Whitehorse, YT with a 2008 F-350. He started telling me how he lost his trailer brakes on the way from Colorado. A Ford dealer in Boise found it to be a corroded factory installed 7 way connector at his bumper, just like mine. He too owns a boat and has submerged it while launching boats. DI-ELECTRIC GREASE is my next purchase. The dealer told me to pack the connections when I reassemble the new plug. Bad ground, and water & electrical do not mix.

[bigbunkhouse]

glad to hear you got it all figured out! I pack the triler side plug with di-electric grease also so it will spread to and protect the truck side. Just be careful with the trailer side because if it hits the ground the dirt and or little pebbles will stick to the grease. I use so much between the plows and trailers I have it in an easy cheeze style can that is pressurized and has a nozzle to get into those tight places