F250 Trailer Disconnected Message

I did additional trailer and truck connector contact cleaning at our final destination using Brasso and flat Q tips. It did a good job of cleaning the contacts and they are bright and shiny. Reconnected trailer to the truck and got "Trailer Connected" message. I wiggled the plug connection, cable going into junction box and all external brake wiring at the axles and hubs and got no disconnect message. Heading back home on first leg of our return trip and so far no disconnect message.

I put the cleaned up trailer plug in a zip lock bag and stuck it under the propane tank cover to keep it dry while we were camping for two weeks.

Lynnmor wrote:
Get one of these, available many places online. Plug Guard

Now that is a good product.

I have one of those gizmos that Lynmore suggested o my flat bed and fifth wheel.

They are the cat's meow. :W

Get one of these, available many places online. Plug Guard

Thanks for the information.

The next morning after the disconnect message I inspected the trailer plug contacts and there was some green corrosion and dark tarnishing on the contacts. Two of the contacts gap spacing were different from the others. I used a nail emery board cut down to contact width and cleaned the contacts as well as pushing the two contacts with a small flat blade screwdriver. I had no more disconnect messages for the last 100 miles to our destination. Will do further inspection on the trailer wiring since we will be at our site for two weeks.

yep, same thing on my flatbed with the wires being chafed going thru the axle.

When running that down i was able to pull a little slack one way or the other at the axle entry points and the signal would go away.

It is very common that the wiring runs down one side of the trailer and then passes through the axle to get to the other side. The inside of the axle is generally not polished or painted. Over time the wires will wear and create bare spots. As the trailer moves the wires bounce around. When the bare spot hits the you will get a "trailer disconnect" warning.

dclark1946 wrote:

Lynnmor wrote:
Your truck is seeing an intermittent connection of the trailer brakes. You need to inspect the trailer plug and brake wiring all the way to the magnets. That includes any wires inside the axles.

So you are saying the Ford trailer system is monitoring the brake circuit only to determine connectivity? Is that continuous or only when brakes are applied and the system monitors current draw?

Yes, the Ford brake controller monitors the brake connect ALL THE TIME.. Not just when you start braking.

Pretty much all GOOD controllers will do this..

As someone else pointed out, you NEED to check your trailer wiring.

Start at the trailer plug, wiggle it a bit, sometimes they can have intermittent connections on the brake circuit and all the lights will work fine..

I take a piece of autobody grade sand paper and fold it over a non conductive piece of plastic or wood and insert that into the trailer plug to shine the connections.. This sands off any corrosion caused by the weather from the connector making a better electrical connection.

If that fails to help then you will have to trace the wiring back to the brake drums..

Typically, the wire will be run down one side of the trailer, then they run wire inside the axle tubs to get to the other side.. This can cause a lot of issues over time since the wire is free to move inside the tube.

The wire eventually breaks causing a open circuit or the insulation is chaffed off causing a intermittent short..

The fix for this is to RUN NEW WIRE on the OUTSIDE OF THE AXLE TUBES, bypassing the wire run inside the tubes.

I had the same message on my truck. It was caused by the brake wiring on the trailer being cut by up/down axle movement. The warning initially would show on rough road conditions. The warning became permanent when the wires were cut. Spliced the wires during a rest stop. No more disconnect warnings.

I had the same problem on my truck. It turned out to be the brake wires inside the axle tubes had worn through in a spot and caused very intermittent issues like this