I've had issues with this as well. When I first hooked up my flatbed, I got the trailer disconnect every 2-3 minutes while driving. I replaced the 7 pin connector, and cleaned the ground but it didn't help. I called the dealer and they blamed my trailer. They said I could come get my trailer diagnosed for a charge.
After doing some reading on the problem, someone said dielectric grease fixed it. I bought some before a long trip and the trailer disconnect stopped popping up! However, now anytime I use the manual brake controller it disconnects the trailer and the trailer gain screen shows no trailer. The controller still activates the brakes, so it's really just more annoying than anything. My biggest peeve about it now, is I spent 50k on a truck, the dealer is offering no solutions and it's not working as it should.

 

I'm going through the same issue right now. Everything's fine when I hook up my trailer, but as soon as I get on the road for a few minutes, I get the trailer disconnect warning.

I took my trailer in to have it looked at, and they said they see this problem quite a bit, and it's always on F150s. Never on Dodge or GMs. They are checking the trailer, but are sure it's something with my truck. For whatever reason, the 7-pin connection on the truck is rotated 180 degrees compared to the Dodge and GMs. Maybe it is a weak connection to begin with, and gravity makes it worse? I'm grasping at straws, obviously.

2016 XLT SCREW 5.0L V8 4X4

 

Are the lights on the trailer flickering when these errors pop up? The Ford connector has a tab that aligns with the one on the trailer connector to "latch" so I would think it's secure in the housing.

I've only pulled my 27' TT once with my new F-150, but it was nearly 600mi round trip to the park and back home. No issues observed. My trailer has about 2000mi on it total. '15 Jayco Jayflight 23RB.

 

So took the truck and trailer to the dealership. They found nothing wrong with the trailer or the wiring. The don;t know why the brake controller is not working with the trailer. They pulled up a new 15 and 16 and hooked it up and both did the same thing as my truck. So there is something with Ford's brake controllers that don't simple magnetic drum brakes. So they have some calls into Ford to try and figure it out but as of now I'm just SOL really. I can hook a $50 brake controller up and they work fine, but the one that comes stock in a $50k truck, yeah that one's not going to work. Good job Ford!

So I'm stuck with partial braking power as I have to leave the controller set to Electric over Hydraulic which is better than nothing. Just upsetting that the whole reason I traded in my 2010 for the 2015 was for increased towing and although I have that now I lost my brakes.. WTF!!

 

Have you tried checking voltage at the connector, then again at the brake itself when you press the brake pedal? This would require 2 people obviously. if you get different readings, you might have a ground issue somewhere.

do you still have your old controller? there should have been a harness in the glovebox to wire up the aftermarket controller. See if it outputs more voltage than the factory one.

 

This is not a wiring problem, it is a software problem. The Ford controller is not seeing the trailer is even connected. My assumption is that the controller uses some sort of load sensing on the brake wiring to tell if a trailer is connected. My guess is the Ohm load on my trailer is outside of Ford's specs on the controller. I can also assume that the Load sensing spec is different between Elec over Hydraulic vs the Standard electric since Elec/Hydraulic uses requires less voltage. So I may try to figure out what the Load spec for the brake controller is and see if I can mimic that load on the trailer wiring to get the controller to atleast see the trailer is connected.

Just to note, I can connect my old Tekonsha brake controller up to the trailer and the brakes work just fine.

 

Ok, looks like you've done your homework. In all honesty, I'm guessing the computer in our trucks is too smart for itself. I remember when trailer break controllers actually hooked a line up to the master cylinder to function properly.a aftermarket controllers just push voltage down the line. Ford getting too smart for itself here. I wonder if there are any variables found by using a forscan.

I'm pulling my TT 480 miles one way and back up to Durango Co this weekend. Will be my first trip pulling it up/down mountains. I'll report back if I have any issues.

 

Any update on this?

 

Little delayed in getting back to this but yes. I just wrote this up and can gladly say I resolved the issues myself no thanks to the Dealership and Ford...

https://www.f150forum.com/f118/trail...8/#post5279115

 

Anybody else have a different fix for this issue with the trailer brakes? I tried Gonzo's fix. I have some braking, but still get message.

I posted more details here:
https://www.f150forum.com/f118/trail...4/#post6904944