Troubleshooting Intermittent Trailer Disconnected Message with Factory Brake Controller on Ford

Question

Question:

The unit toggles back and forth between connected and disconnected. First it’s a new trailer and it does it on other trailers too. Both the trailer plug and the female plug on the vehicle have been cleaned with spray contact cleaner and then I used Deoxit on the contacts. I think the controller is sending out a signal and is not receiving the proper response from the trailer brakes. Either too little or too strong. This problem is extremely intermittent. Controller seems be working regardless of the display of connected/disconnected. Any idea on how to fix this? If I need to replace controller is there one that would fit without being mounted under the dash? Am I possibly losing the ground between hitch and ball as it does not cycle back and forth when stationary?

asked by: Jim S

1

Helpful Expert Reply:

The "Trailer Disconnected" error message on the dash with a factory brake controller is usually related to an issue with the blue brake output wire that runs from the brake controller to the 7-Way connector. The fact that the issue remains constant with multiple trailers indicates a problem on the truck side.

You have already done a great job of inspecting and cleaning both the truck and trailer side 7-Way so next you will want to try and inspect the blue wire coming from the back of the Ford's 7-Way. Try and trace the wire as far as you can up towards the cab and look for any frayed or pinched areas that need to be fixed/replaced.

It could potentially be a ground issue on the trailer but this seems unlikely since you've pulled a few different trailers and had the same error message on the dash with each. On your primary trailer though you can try checking the main ground wire at the connector as well as the individual ground wires coming from each brake assembly. Make sure they are all attached to clean, bare metal surfaces on the trailer that are free of any debris or corrosion.

If you still can't locate or resolve the issue please let me know and we can continue to troubleshoot.

This type of issue doesn't really indicate a bad controller but if you do decide to replace it now or at some point in the future a really nice option is the Curt Echo # C51180. This is a unique controller that actually plugs into the truck's 7-Way and then pairs to your smartphone via Bluetooth. This eliminate the need for a separate component mounted in the cab since your phone is what you will use to adjust any settings or activate the manual override.

I have attached a short video demonstration that you can check out as well.

expert reply by: Chris R

1

Manuel R.

3/27/2024

Very helpful thanks

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Chris R.

3/28/2024

@ManuelR Glad I could help!

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Dennisr

7/10/2025

@ChrisR I just installed the Curt 51200 inline Echo brake controller. Without a trailer connected and driving my trailer connected and trailer disconnected lights come on and off. I talked to a Curt troubleshooter over the phone and he told me that Ford uses resistance to determine if a trailer is connected or disconnected. With the inline controller installed it messes with the resistance in the wiring causing the light issue. He wasn't sure if there was a way for a Ford technician to recalibrate the system with the added controller.

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Nick S.

7/10/2025

@Dennisr I have heard some people with a similar issue taking their vehicle to a Ford dealership. I believe there is a setting or something in the electronics that they can "unlock" that could fix that issue. I believe its a setting that when it comes out of the factory is not able to accept a after market break controller. I would recommend reaching out to Ford to see if that is something they can do.

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Tobey

4/12/2024

Hi, I am having a similar issue, I have a 2019 F-350 superduty, all my trailer lights work but when you manually squeeze the brake controller on the factory controller it chimes on dash trailer disconnected, also when pushing the +/- gain button you have to push it 1/2 dozen times before it works, does this sound like a bad controller or also a possible wiring issue? Thanks!

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Pete F.

5/9/2024

Hi Chris, I'm having the "trailer disconnected from vehicle" warning on my 2016 F-150. It doesn't happen all the time but once it starts it goes off multiple times. I don't think it has anything to do with the brakes. I can be driving down the hi way, not touching the brakes or the controller and it will go off. I have cleaned the terminals on the truck 7 pin and the trailer (2016 Grey Wolf 26DJSE). Any idea's what this could be?

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Chris R.

5/9/2024

@PeteF It's fun, right? I honestly don't know what else you could really check on your end. My next suggestion would have been to make sure both the F-150's and trailer's connector pins are clean, but you've already done that. That being said, even if you aren't touching the brakes, the blue output wire could still be the culprit. There's always going to be a small, pulsing power that gets sent along this wire to constantly check for a trailer connection, so if that's not happening, that could be the problem. I'd still check to make sure that circuit is in good condition.

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Petef

5/10/2024

@ChrisR Thanks. I will double check the pins and look at the blue wire.

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Seth M.

7/14/2024

@ChrisR Hi I have the same issue is there a way I can turn off the warnings on my screen all together?

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See All (5) Replies to Pete F. ∨

Corey

6/26/2024

Hello, I have a 2014 f150 xlt, I added a break controler and had ford unlock it. I have hooked multiple trailers up and all lights work, but my truck says no trailer. I have replaced the wireharness from above spare tire back to trailer connection. Any ideas ? Thanks

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Cody L.

7/23/2024

I'm having the same issue. All my lights work on trailer but no brakes. I've connected to 4 trailers, and it did register one for a few min then disconnected. I have had 2 other truck hooks to my trailer and they picked it up instantly. I have a 2014 F250.

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Chris R.

7/24/2024

@CodyL Hey Cody, so at least we know the issue is on the truck and not the trailer. Have you tried testing the brake output pin on the 7-Way when hitting the manual override? I'd also inspect the pin itself for any debris or corrosion. Sometimes all it takes is a little cleaning to get the connection back up and running.

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Chinggis

2/5/2025

@ChrisR 2019 F250 is showing a "No Trailer" or "Trailer Disconnected" error when trying to connect a trailer. After replacing the TBC (Trailer Brake Controller), the system works when the gain setting is at 0 or 1, but when the gain is set above 1, the brakes lock up. You've already checked all the voltages, which are normal, cleaned the connectors, and confirmed that the fuses and relays are functioning properly. Now, im wondering what to do next.

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Jameson C.

2/5/2025

@Chinggis If you put a multimeter on the output circuit when the brakes are locking up that would be a good place to start. The lower gain levels should be much lower than 12 volts but if you are seeing the voltage spike really high when getting above 0 or 1 that would be concerning. Have you adjusted the brakes recently.

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See All (5) Replies to Cody L. ∨

Eric S.

8/4/2024

I have a Jayco 145RB RV and I use 2019 Ford F150 to pull it. When I’m at full stop the trailer is connected but as soon as I start moving the dashboard says “trailer disconnected”, all lights seem to work though. So when i stop the dashboard gives a message of “trailer connected”. I cleaned and dielectric lubed both trailer and truck connectors. My friend used my trailer and had the same issue, so I’m sure the problem is with the trailer. Any ideas what to look for?

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Chris R.

8/5/2024

@EricS That's an interesting one. I'm leaning towards a weak ground connection somewhere that's showing itself when the trailer starts moving around. I'd maybe check the ground wires at each of the brake assemblies to make sure they're still securely connected to clean, bare metal. Let me know if those look good and we can keep going.

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Steve

8/30/2024

Hi Chris. I am having the same kind of issue with my new 2024 f350. We just finished a 5600 mile trip pulling my new fifth wheel with no problems. Since being home the only thing that changed was I had hydraulic disc brakes put on and I plugged some led strip lights into the trailers four pin. We just went on a trip when the trailer disconnected message came up. It always seems to happen when we are nearing a stop and I let off the brakes. I feel like the brakes are working fine and they work with the controller squeeze lever. It’s just odd this message has started appearing. I did clean the terminals on 7 pin and applied dielectric grease. Haven’t towed again yet to see if it works. Any ideas? Thanks

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Chris R.

9/2/2024

@Steve Hey Steve, did you have standard electric brakes before and just now changed over to an electric over hydraulic setup?

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Steven

9/2/2024

@ChrisR Yes standard electric drum brakes on the trailer and now electric over hydraulic disc brakes.

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Chris R.

9/3/2024

@Steven Got it! It's possible the factory controller on the F350 isn't playing nice with the new setup. Make sure you change the setting to EOH on the controller if it lets you.

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See All (6) Replies to Steve ∨

Brian P.

10/26/2024

I'm having a similar issue but this time the problem is isolated to a trailer. at high speed I can tell the brakes are working but when I slow down or stop the trailer brake disconnection pops up. Having this issue on my ram 2500 but also tested with a Nissan Titan XD and ford f150

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Chris R.

10/26/2024

@BrianP That's an interesting one. Have you checked the ground wires at brake assembly? Make sure they're still securely attached to clean, bare metal. Weak ground connections can do all sorts of weird things.

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Premier S.

4/29/2025

The truck works fine on multiple trailers. It’s just this one particular trailer.

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Chris R.

4/29/2025

@PremierS Interesting. That certainly tells us the issue is somewhere on the trailer side. I'd start by checking the ground wire coming from each of the brake assemblies. Make sure they're all attached to clean metal surfaces or ran up to the trailer's main ground. Also inspect the trailer's 7-Way and clean it of any debris or corrosion that might be built up inside or around the pins.

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Answer 1

Hey Justin, yes the TST Sensor part #TST47FR does work with your TST 770 monitor that you have and would work great.

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Answer 2

You are correct, you should only be getting output when the brake is applied, or the override switch is activated. It sounds like the controller might be bad, but to make sure, you should probably bench test it before tossing it. Use a circuit…

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Answer 3

If the controller is working fine with one trailer and not with the other then the problem is most likely with the trailer and not the truck. I would start by checking all of the ground connections on the trailer, especially the ground at the coupler…

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Answer 4

Assuming that when you tested the resistance of the brakes you were testing the two wires on each magnet and getting 2.0 and 2.8 ohms the magnets on your trailer are not working correctly and will need to be replaced. For 7" brakes you should…

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Answer 5

The issue you described sounds like a problem on the trailer side wiring. I have attached the wiring diagram of the Titan BrakeRite EHB Electric-Hydraulic Actuator part #T4813100 for you. The first thing you will want to check is the blue brake…

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Answer 6

It is not uncommon for certain factory brake controllers to have issues with electric over hydraulic brakes. This would be the first we have heard of this issue with a 2023 Ford F-350, but it is possible that the brake controller in your ford is…

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Answer 7

I might have an option for you but we don't offer any flush door latches with an extended striker. However, the Full Size Locking Steel Flush Door Latch part #L3980 matches your door cutout at 4-5/8" long x 3-3/8" so this is our best…

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Answer 8

The Moryde wet bolts #MR52HR use a standard 1/4"-28 thread for the zerk fittings.

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Answer 9

From that number you supplied, it appears you have axles that are 5,200-lb to 6,000-lb with a 12" - 6 on 5-1/2 bolt pattern. For brake assemblies I recommend #AKEBRK-7R-SA for the right hand side and #AKEBRK-7L-SA for the left. This is a…

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Answer 10

The brake wire providing voltage is wired in parallel, with one lead from each magnet being grounded to the trailer frame. We have a great Wiring Help Page that shows a diagram, I will provide a link to it below.

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Answer 11

The correct set of replacement brake assemblies for your AxleTek 12 inch assemblies is the kit part #AKEBRK-7-SA that you referenced. This kit is a pair of left and right assemblies that are an exact match to what you have that are also self…

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Answer 12

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

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