2020 Expedition Trailer Wiring Fault

On Sat 1/23 we picked up our brand new Imagine 2800BH. After the walk through the sales guy drove it off the lot to a lot behind the dealership and we were about to do a "test drive". When I got in I noticed a Trailer Wiring Fault on our 2020 Ford Expedition. The Expedition has the max trail package with integrated trailer brake controller and the pro backup assist. I asked the salesman if it was an issue and he said he wanted to ask the shop guys about it. After about 10 min he came back and said they looked it up and that its an issue with the Ford software. Said that everything is working and we just need to take the Expedition in to get the software updated. We had already planned to take the vehicle to the dealership this week anyway so everything was going to work out. The dealership said there is no issue with the Ford. I don't trust them though. So, now I've read through all the forum posts I can and just wanted to get folks opinion.

Here is what I am planning to do. I would love advice.
1. Hook the Ford up to a buddy's travel trail and see if the fault appears. This should tell me if its the Ford or the trailer
2. If its the Ford, push the dealership harder.
3. If its the trailer, maybe hook it to my buddy's truck and see if he gets a similar fault. He has a Chevy.
4. After reading the other threads on this I will have some troubleshooting to do.

This trailer is brand new and had probably only been on the lot for a month or two due to demand, is this more likely to be a trailer or tow vehicle issue?

I got that once when a spider built a nest in the 7-pin plug on the TRAILER. I forgot what pin # it was.

I blew it out and then cleaned with q-tip and then toothpick. Never had the error again.

This year I will be using contact cleaner and then adding some dielectric grease to my connectors.

Good luck and congrats!

Yesterday I plugged my buddy's travel trailer into the Expedition and got the same message. I now believe its the vehicle and not the trailer. I don't think the dealership did any testing at all.

Took the Expedition back to the dealership. So far they say they're unable to check the wiring fault. I'm guessing they have checked anything other than to see if there is a error code stored. No code.

check for loose ground on trailer 7 pin connector and wiring. most of time its a loss of ground in the wiring.
and trailer builders usually flubb the ground part,

i can say over the past 15 years with ford vehicles with built in trailer brake and wiring, its almost ALWAYS the loss of ground in the trailer pigtail
does your dash give you a trailer connected then a disconnected?

if it returns with different trailers, check the harness that plugs into the vehicle receptacle for secured fastening

ford has a load shunt to check brake power to a trailer, and a plug in test unit for the vehicle

It does not give me a connected, disconnected message. We just get the fault message when we plug it in. I also got the same message when I plugged in my buddy's trailer.
When we press the brakes the trailer brake "gauge" will start to increase but then immediately go to zero.

Jesse Sutherland said:

It does not give me a connected, disconnected message. We just get the fault message when we plug it in. I also got the same message when I plugged in my buddy's trailer.
When we press the brakes the trailer brake "gauge" will start to increase but then immediately go to zero.

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it may sound simple, but did you look inside the trucks plug and made sure no foreign items . and to make sure the connection points are aligned with the trailer pig tail connection.
also double check the pig tail is seated fully and the lid locks down on the pig tail.

other than that i would borrow buddies trailer after i did a deep check of his wiring and then go see ford with trailer hooked up and let them run diagnostics, something is amiss

last time i rewired my hauler trailer with new led lights, i kept getting lights on, then fade then messages of trailer disconnected

found a ground on the light itself not making good contact

Did you ever resolve your issue? I'm having something similar and would be interested to hear what the solution was for you.

First thing

Jhesse77 said:

Did you ever resolve your issue? I'm having something similar and would be interested to hear what the solution was for you.

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I'm not the OP, but had the same / similar problem Here is what I did to resolve.

First inspect your 7 pin plug and socket. Clean all connectors on both sides and retest.
If problem still exists, try your truck on another known good trailer and then
try another known good truck on your trailer, could be the same friends truck and trailer, which is what I did.

If your truck has the same problem on the other known good trailer and the other truck does not have the same problem on your trailer, then it is prolly your truck, see #1 below.

If on the other hand, the other truck has the same problem with your trailer, it is prolly your trailer, see #2 below.

#1) Drop the spare tire on your truck and follow the white wire from the 7 pin trailer plug to where it is attached to the frame above the spare tire well. Remove the wire, clean the connector, bolt and spot on the frame thoroughly. Reinstall and tighten well. If this does not resolve the problem (it did with mine) look into upgrading the TBC firmware and / or replacing the TBC itself, others have resolved their problem with these solutions. Also inspect the TBC harness from the back of the truck forward for any damage.

#2) It is probably a ground on your trailer. Unfortunately the way most trailers are wired there is both main grounds found shortly after the 7 pin connector cable enters the trailer frame as well as a local grounds at every light (tail and marker). You will need to go through every one of these, remove, clean and reinstall. I used a 12V battery with test leads attached to various pins the 7 pin connector and then at each light to test. Another possible issue with the trailer (which happened to me at a different time) was I was not getting my trailer left blinker / turn signal. After confirming the light itself was good, I traced the wiring harness from the front back and found the harness had 3 couplers, 1 of which had partially pulled apart causing the problem.

Good luck, I hope this helps

Thank you, I got one ground cleaned up on my truck side and it for a little bit then I got the fault again. Looks like there are two grounds in your second picture. I didn't catch that on mine. I'll drop the tire and get a better look. Thank you for the suggestions!