2019 Chevy Dually - Trailer Brake System message

[Mikendebbie]

This message has been popping up more and more lately. Yesterday I was on a rough gravel road and it was popping up and going away every few seconds. Got on the highway to head home and it did not come up again. By the way - I have not had the Monte hooked up to the truck since July 2023. Message comes up with nothing plugged in.

My guess is there is a loose wire in the bed plug or on the lower hitch plug. Can anybody advise what to do to fix this?

[AZ Traveler]

Mike,

We need a little more info to help. What message are you getting? Only without your trailer connected?

[Daryles]

Try cleaning the contacts on the 7 way cable AND the receptacle in the truck bed.
We had intermittent messages "Connected", "Disconnected".
I used # 200 sand paper and "Deoxit" contact cleaner. For the female contacts I rolled up the sand paper. Once done I took a needle nose pliers and squeezed the female contacts a bit tighter.
We haven't had a problem since.

[Mikendebbie]

Hmmm…I’m going to play closer attention to it next time. Don’t remember if it says “connected” or anything else. I usually press the “dismiss” button on the steering wheel.

To be clear - NOTHING is plugged in to the truck…NOTHING! The message pops up at random times, but never as many times as yesterday when I was driving a rough job-site road. It has been happening for the past 2-3 weeks. I have a cooler strapped in on the plug side of the bed. My first thought was that the cooler has rubbed it the wrong way.

[DutchmenSport]

I've had the exact same problem twice with my 3500 Chevy Dually. It turned out to be a relay switch, located mid may between the controller and the 7 way plug.

This is one of those areas that's hard to diagnose. But knowing the history of my own truck now, that's where I'd start to look for a solution. You may have to take it into your local GM dealer and have them trouble shoot it. Having non-dependable brakes on the trailer is a very dangerous way to travel. Fortunately for us, the first time this happened I was towing and over a thousand miles from home. I limped the trailer to our next campground destination (without trailer brakes) and was able to get to a GM dealership that fixed the problem. I say this was good, because the trailer brakes stopped working completely. I knew they were not working and adjusted my driving style accordingly. Having them work intermittently would be a disaster, never knowing when stepping on the brake peddle if the trailer brakes worked or not!

The second time it happened, I was not towing when the error occurred. I didn't hesitate. I went straight to my local GM dealer, told them what I thought the problem was, and an hour later drove away. It was the same part, that brake controller relay under the bed of the truck.

Your's may be different. Good luck though. Problems like this are very hard to figure out on your own. The electronics in today's vehicles are near impossible to troubleshoot. It isn't like it use to be 50 years ago!

[Mikendebbie]

Thanks Dutch!

[Foldbak]

That's good info Dutch. I've heard that there has also been problems with the infotainment head unit. Make sure your firmware is up to date.

[TK1]

Originally Posted by Mikendebbie

This message has been popping up more and more lately. Yesterday I was on a rough gravel road and it was popping up and going away every few seconds. Got on the highway to head home and it did not come up again. By the way - I have not had the Monte hooked up to the truck since July 2023. Message comes up with nothing plugged in.

My guess is there is a loose wire in the bed plug or on the lower hitch plug. Can anybody advise what to do to fix this?

We have had that same message pop up twice on our Silverado 3500 and both times it was due to a failed trailer brake relay located on the driver side frame rail just above the rear wheel (GM part # 20904439 you can get one from Amazon for $38.00) it only takes about a 1/2 hour to replace it.

[DABOO77]

You might take the trailer plug in apart - truck side obviously and check for loose connections/ corrosion. If you live any where close to the rust belt, I've seen green uglies growing inside of the plug in. At that point, cut / strip wires back to good copper and replace plug in. Just an idea before spending to much $$$ replacing parts. These newer vehicles are very sensitive to ground side resistance in electrical circuits. Retired mechanic / 40 + years,, seen this multiple times. just an Idea. Good luck.