What causes "Trailer Disconnected" message?

[bmtndog]

I have a 2015 Ford Expedition with the integrated electric brake controller system. When I connect my small travel trailer and start the engine, I get a message on the info panel on the dashboard "Trailer Connected". (This is always good news.) However, as soon as I start to pull the trailer, I get a message "Trailer Disconnected" along with two "dings". When I slow down to a stop, it reconnects (and "dings" once). As, I accelerate from the stop, I get the disconnected message again. This thing is constantly dinging and telling me the trailer status connected/disconnected/connected/disconnected and is driving me crazy.

The brakes seem to work fine, even when the status is "Disconnected".

I need to get this figured out and fixed.

I've used a tester that has a "trailer simulator" and have no problems. All lights work on the trailer and as I said, the brakes seem to work fine also at all times.

So, I guess I need to know what it is that the truck is detecting that would make it think the trailer is "disconnected"? Then, I can try to figure out what is exciting that failure mode from the trailer (assuming it is not some kind of wiring fault or logic fault in the controlling software on the truck).

Can anyone tell me what is happening when I accelerate that would cause the truck to think the trailer has become disconnected? Any tips on how to troubleshoot this? (The dealer has tested the wiring and say's all seems good.)

 

[Bedrck47]

check the wiring on the trailer to make sure everything is tight Pay attention to the ground connection on the trailer It almost sounds like you could be loosing a ground between the expy and the trailer

 

[stamp11127]

Second on the ground. You can make a short jumper to connect to the tongue and the hitch to test.

When you accelerate, the hitch will move if you are using a receiver type & the ball will move slightly forward in the tongue if not latched tightly. The grease may also cause a loss of ground if overloaded. Some grease is good, gobs of it isn't.

 

[bmtndog]

I will check ground

I bought some wire and alligator clips this week. This coming weekend I'll rig up a jumper between the truck body and trailer body, and will let you know if that makes a difference. I guess the challenge will be finding good connection points.

 

[bmtndog]

Tried grounding experiment with no success

Over the weekend I spent several hours on an experiment to test the grounding hypothesis. I took about 15' of 16 gauge wire with charging clips attached to each end. I connected one end to what seemed like it should be a good ground on the chassis of the truck and the other end to the tongue on the trailer. I did this three times at three different sets of connection points to ensure I was finding a good electrical path to ground.

In all three cases, I still got the "trailer disconnected" message as I accelerated. So, while a very promising hypothesis, good grounding between the truck and the trailer does not seem to be what excites the error message.

Thanks for the suggestion. I'll keep working on this.

 

[stamp11127]

I still will go with a ground problem.

Integrated Brake Controller-Message trailer disconnected - Ford Truck Enthusiasts Forums

 

[bmtndog]

Grounding sounds like such a likely candidate. Is there any way this could be a problem with the truck wiring, such that the control system in the truck is not well grounded to the truck chassis?

I ask because there is one more piece of data for this puzzle. Last May, when the truck was pretty new, we were driving on I80 near Laramie, WY and an error message came up on the info display "Trailer Wiring Fault". We were NOT nor had we ever, up to that point, towed a trailer! I dismissed the warning and it has never occurred again.

While in Laramie, we were staying at our cabin which has "critters". It is not unusual for a pack rat or squirrel to get into the engine compartment and chew on wires.

I see no visible damage, nor did the service techs at the dealership. But, this has me wondering if maybe a wire that grounds the brake control system (including whatever sensing is done to detect the trailer disconnect) is intermittent?

 

[bmtndog]

A quick update on this. I pulled a different trailer with the truck and did not get the Trailer Disconnected error. This seems to narrow the problem to the trailer. However, after about 10 hours of work on this, we can't find anything wrong with the trailer. All wiring is sound. We've tried a variety of grounding schemes and none make a difference. The brakes themselves are in great shape...About to give up and just live with the annoying "ding ding ding" and disconnected/connected message each time I start or stop.

 

[reece146]

Either connector, bad ground or broken wire... not much else it can be.

If it were me I'd probably attempt to fix/replace the trailer side connector and the first 12" or so of wire behind that... if I was convinced that grounding is not the issue.

2¢

 

[Bedrck47]

Don't know if this would make a difference but were the lights LED or Regular lights on the trailer that you have a problem with and what were they on the trailer that gives you no problem

 

[bmtndog]

LED lights on the troublesome trailer. Normal lights on the trailer that worked.

We also wondered about the LED lights, but they don't dim when this happens (from the perspective of a following car), all connections are good, no significant voltage drop when standing still...

 

[Bedrck47]

Well the only thing to do would be to try on another trailer that has LED lights and see if it happens there also.
Compare apples to apples so to speak

 

[bmtndog]

Based on some info from Ford, the problem can only be with the brake controller wire or ground (below), so that rules out the lights.

Every 4 seconds (when not braking) the TBC module sends a voltage pulse to pin 3 of the 7-pin trailer tow connector to determine if a trailer is connected to the trailer tow connector.

Current thinking is that one or both brake modules is "bad" in that underway, when the tires are spinning, the resistance is high. Can't explain that yet, but I am taking the trailer to the trailer dealer in a few weeks (multi-hour drive one way). And, he thinks he has a way to test for this.

 

[Bedrck47]

Thanks for the update

Still would be interesting to know what would happen if you hooked to another trailer that has led lights

 

[Bedrck47]

Strange Look at a trailer connector wiring diagram Pin 3 is for the trailer lights?

 

[Bedrck47]

Another question for you Was the connector on the trailer a 7 pin connector or a 4 pin connector and did you use a 7 pin to 4 pin adaptor

 

[bmtndog]

Okay. That is weird. I did not think to verify that pin 3 is to the brakes! I just assumed it was. Bad assumption. So, we are back to the theory that the LED lights may be the issue. I am hauling the trailer back to the dealer in January sometime where they have more trailers we can pull to test.

The trailer has the 7-pin connector.

 

[Bedrck47]

The pic I posted may be wrong Ford wiring diagrams show something different in the pin connections

 

[bmtndog]

I think the pin numbers are different although the locations are the same. The Ford manual shows "3. Blue" = "Electric Brakes", even though the photos I've seen online call this pin 2 on the connector. So, I think it is important to go by the color code, not the pin number. Doing that, the Ford TBC sends a test voltage to the "blue" wire every 4 seconds. Again, likely eliminating the LED lighting as a culprit.

 

[Bedrck47]

When you find the cure Update the results as it will help others