Daniel Stanavich

Hey there, this issue was a pain to find accurate information on so I will post this here for others to see.
I bought a used 2015 F-150 XLT and a brand new travel trailer shortly after. The truck would ding saying "trailer disconnected" and then ding again showing the trailer break gain. This happened consistently every few minutes sometimes and other times is would be hours in between. It happened when cruising, accelerating, breaking and turning. No rhyme or reason. My trailer breaks worked still and the lights on the trailer never went out. I took the truck into the local Ford dealership and they said ford had a software update for the integrated break controller, when I picked it up and went and hooked up the trailer, the messages had stopped and the trailer breaks worked fully. What I hadn't realized was the trailer breaks were working but not very well, I couldn't lock the trailer tires up on full gain, but after the software update I can fully adjust the gain from low to locking up the tires. I looked everywhere online for a fix to this and couldn't find one, so here is mine. Hope this helps someone out.

ks54703

Also had trailer fault light issues for my trailer with all LED lights on a 18 F150. All of the LED lights worked on the trailer but was intermittently get the fault code on trailer lights.Turned out to be the factory plug needed a little Spray Lube to make a better connection.

Johnny_bravo00

Brakes > Breaks.

Glad the dealer had a quick fix for you. That's not always the case.

Daniel Stanavich

Wow... wish I could blame that on autocorrect but I don't think I can. Thanks for the correction.

As for the electrical connections, this was the first thing I did. Cleaned and greased connections from the front to the rear bumper with now avail. I am glad that you were able to solve your issue on your own.

Skeptical J

With our brand new Ford Edge they greased the flat 4 plug at the factory. When I connected the trailer lights, they all worked but I got a warning in the dash that they weren’t. A bit of clean up of the plug and all is good.

Jenny Wilder

QUOTE
You got the update from a Ford dealership? Free? Cost? I have same issue with 2015 f150.

Scott_R

I am having the exact same issue as described in the OP on a 2017 F150. It only happens on one trailer. I rented a dump trailer over the weekend, and it worked perfectly. I also have a camping trailer (KZ) that works perfectly.

Since the problem only occurs with this one trailer, I assumed it was the culprit. I just bought a new connector and wired it. Ensured there was a good ground connected also. Same problem. I would really like to figure this out.

Maquis

I have the same issue with my 2017 - one of three trailers periodically disconnects.
First, there is a TSB from Ford about this (I don't have the number). I took my truck to the dealer and they replaced the connector on the truck per the TSB. I doubt you can get it done no-charge now that your truck is out of warranty. Since it's only one trailer, it probably doesn't fix your problem anyway. With me, all trailers did it before the TSB was applied.

I would LOVE to know exactly how the truck is detecting the trailer - I've searched all over and never have found an answer. It would certainly make troubleshooting easier if I knew what the truck was looking for. When mine says 'disconnected', the lights and brakes still work.

I fixed one of my trailers by replacing the lights - whoever installed the old lights had a wire pinched that would intermittently short to the frame.

Bottom line - if it's one trailer, there's an issue in the wiring somewhere. I plan to completely rewire the one trailer of mine that has the issue. The frustrating thing is that this trailer has been pulled with a Tundra and a Chevy without issues. The Fords seem more sensitive to wiring issues.

rolofung

One more data point:

I recently started towing regularly and this was bugging me. My trailer has electric brakes, and with "electric/surge/none" selected, I was experiencing the following symptoms:

• no reading in the brake meter on the dash when braking
• "trailer disconnected" message whenever the TBC was activated manually
• very light, if any, braking felt in the trailer

I brought it into the dealership today and they updated the trailer control module. Problem appears to be fixed! Getting good brake response via foot brake and the manual control, and the brake meter now works as expected.

Parthery

I too had the issue with my '18 F150. Turned out to be the plug in the bumper. Took it to the dealer who wanted me to bring the truck in with the boat/trailer attached. For $26 I ordered a new connector and swapped it. Problem solved.