Trailer brake message

[Canadiansteelman]

Our situation with our 2020 GMC 1500 sounds similar. We got a trailer brake message while on the road with our previous trailer. The fix was replacing the brake wiring that ran through the axles to the right-hand brakes. I didn't use a meter, however, the message never returned so I assume it was shorted wiring.

Jim

I had the same problem with my 2020 GMC 2500HD. Had truck in dealership, couldn’t find any problems. In the end the problem was the wires that ran through the trailer axle that feeds the brakes. Those wires were intermittently grounding out inside the axle causing the message to come up on the truck message screen and the loss of the trailer brakes. After taping up these wires with electrical tape, I have not had any more issues after several trips out with the truck and trailer.

 

[SkeetandJudy]

Hello all

I am having an unusual problem and hoping someone has run across this before and can help me out. I am on a cross country trip and one day my DIC display on my truck chummed in saying "trailer brake wiring disconnected". I pulled over and checked my 7 pin plug. I pulled it out and reconnected it and made sure it was locked in. I hit my dismiss button and it went back to normal. A few miles down the road and again it chimed in saying "trailer brake disconnected". This time with an annoying ding. The radio display said "trailer brake gain recalled". I hit the okay button and it starts all over again. The annoying chime. After 500 miles it quit.

I stopped at a trailer shop and they said it could be your ground. They checked all wiring in my 7 pin junction box to see if anything was loose. They checked underneath the trailer and checked all visible wiring. They checked to see if the wires that run through the axles if it was cut or scraped. All was well. They did add another trailer ground from the 7 pin adapter.

Back on the road again and everything was okay because after 300 miles everything seemed normal. I was actually proceeding down a 7% steep grade when it started all over again with the messages and the chime and the ding. I know I had trailer brakes because it was keeping me at 35 mph.

So i took the truck without the trailer into the GM dealer. They scanned and found a fault code for the trailer brake control solenoid. They inspected the harness and found no problems with it. checked the trailer brake control solenoid. They installed a trailer simulator tool. (apparently its a special tool that simulates as if a trailer was attached) They test drove the vehicle 30 miles and checked to see if there was any codes. No codes were found. They let it sit a while and connected the 7 pin tool to the outside bumper plug and drove the vehicle another 60 miles with no problems. They scanned the vehicle and no fault codes.

Back on the road and after a few hundred miles we start all over again with the messages and the annoying ding and chime.

Has anyone had this problem before? I really don't know what to do next.

We have a 2015 Silverado 2500 HD High Country pulling our 2018 Solitude 375RES home and experienced similar error messages. Dealers couldn't figure it out, we checked everything like y'all did and finally a mobile brake technician near Ho Hum Beach, FL figured it out and simply replaced the brake control module located up under the spare tire. No more error messages.

 

[Canadiansteelman]

Had the same problem over two different GMC 2500HD trucks. Tried all kinds of things with the trucks and the trailer and finally found the problem was the brake wires going through the trailer axle. They were shorting out intermittently. I taped them up with electrical tape and no more problem.

 

[Dragfam1127]

Anybody else have that message while just driving with no trailer?

Using the Kentmoore (GM tool) trailer simulator tool eliminates half of the electrical trailer system. This will give you direction in what half is the root cause of the issue. A big factor to remember is the tool plug and wiring are 1/3 of the weight of the actual trailer wiring. I do own the Kent Moore tool this is how I know the comparison

 

[NAKemp]

Last I heard, the current factory fix is replacing the '24 brake controller with a '23 one.

This is happening on my early 2023 gmc 3500 unfortunately.

 

[harell]

We have a 2020 Ram 3500 and a 2020 310gk. We got the message ( brake disconnected) and i spent 6 hours troubleshooting the brakes. I found that the problem was the right rear brake. We found a transport garage that pulled the wheel and brake drum. They found that the wires feeding the magnets was out of place and would short to ground intermittently causing the message to show. Repaired wires fixed

 

[reubenray]

When this happens do you actually lose the trailer braking capabilities? I got the "trailer disconnected" once with my previous Forest River trailer. I have not taken a trip in my new Reflection trailer.

 

[2Amy4805]

SkeetandJudy

You stated that you replaced the brake control module located up under the spare tire. I took my spare tire down and i really didn't see anything related to the brakes. Could you elaborate on that please.

Thank you

 

[harell]

I don't think the brakes will work when the wires are shorted to ground. Because the problem is intermittent the brakes may work when the warning is not illuminated. If you are able to determine which brake is at fault, disconnect and separate and insulate the 2 wires feeding the brake. The remaining brakes should work..but the brake still has to be repaired asap. We were lucky in that the dealer we went to could not take us for 3 months but the big truck repair garage told us that they could take us as soon as we got there. A big thanks to Bensons of cornwall ontario

 

[retired_engineer]

I would run into intermittent trailer disconnected and brake warnings on my old 2015 F-150 shortly after buying it. The problem was caused by moisture getting into the backside connector that connected the wiring harness to the 7-pin connector in the bumper. To fix it I opened up connectors, sprayed them with a moisture removing contact cleaner and put on a thin layer of dielectric grease. I never had a problem after that. I don't know how GMC handles their wiring but it is worth checking.

 

[GoodScout]

We've had the same problem and have narrowed the problem down to our 2024 2500HD. We were able to pull our 2670MK home fro the dealer with our old 1500 with no issues. As soon as we hooked it up to the new 2500 we started getting that irregular Trailer Brake connection warning. Our dealer initially claimed it was a problem that a software update would fix. It went away for awhile, but on our most recent trip it came back. We did try the electrical grease, but it didn't help.

It's going back in Monday, and I'll take the recent info posted above, although our dealer isn't the most up to date on this stuff.

 

[Dutchman2]

SkeetandJudy

You stated that you replaced the brake control module located up under the spare tire. I took my spare tire down and i really didn't see anything related to the brakes. Could you elaborate on that please.

Thank you

See attached video. https://www.youtube.com/watch?v=BOjoHIO-oh8

Dutchman2

 

[eeshelman]

brake disconnected message fix

Thank you for all your information. I am going to turn my solar panel off while I am driving.

I had a similar problem on my 2022. I had a mobile tech check the brake wiring when packing bearings. Although he didn't find anything wrong, the act of moving the wiring around make the problem go away. It has not come back in 8 months and 6,000+ miles.

 

[coltss]

When this happens do you actually lose the trailer braking capabilities? I got the "trailer disconnected" once with my previous Forest River trailer. I have not taken a trip in my new Reflection trailer.

Yes we did, not a good feeling driving through mountain passes.

 

[reubenray]

Yes we did, not a good feeling driving through mountain passes.

My first trip has some decent declines which is why I asked. It would seem like Grand Design would have a recall on this issue (if it is the RV fault). From these responses some are the RV and some are the truck.

 

[bossman2024]

I just ran in to this exact same issue on my way back from Miami this past weekend and Grand Design support told me to disconnect the solar. When the issue happened I had ZERO trailer brakes (thankfully it's flat as tack in Miami!). Turning off the solar initially did not fix the issue, and we started the process of finding a mobile service tech when the trailer brakes came back. I suspect it is the voltage issue as I have Lithium batteries in my trailer and the Grand Design tech said the brake controller gets confused if it sees > 14V coming from the trailer which it would with the solar charge controller if it is doing a bulk charge on the batteries (absorption charge would only be 13.6V so may not trigger the issue). Also I suspect it took a bit of battery drain from the fridge for the voltage on the trailer batteries to drop back down and hence the delay between turning off the solar charge controller and the trailer brakes coming back.

I had a couple of instances on the return trip where I got the same message again briefly about trailer being disconnected after getting gas, but it lasted only briefly and the trailer brakes were working.

I am considering the idea of putting a diode in there as suggested earlier in this thread so I can still have the solar panels charging while I am driving as it's nice to have the batteries fully charged when you get to your destination.

However, I also have been getting a strange error message from the Lippert One Control app as my trailer as the Lippert ABS brake controller system in it. Initially I thought perhaps these were related, but now I am thinking they are potentially not related at all. Has anyone else seen this message?



Strangely I get this message from the One Control app on my phone while the trailer is out in the driveway attached to shore power (ie: batteries are charging) and I get no other information in the app. Just the notification that pops up on the phone. The diagnostics screen just sits and spins so I cannot get any more information about what this means.

 

[reubenray]

I just ran in to this exact same issue on my way back from Miami this past weekend and Grand Design support told me to disconnect the solar. When the issue happened I had ZERO trailer brakes (thankfully it's flat as tack in Miami!). Turning off the solar initially did not fix the issue, and we started the process of finding a mobile service tech when the trailer brakes came back. I suspect it is the voltage issue as I have Lithium batteries in my trailer and the Grand Design tech said the brake controller gets confused if it sees > 14V coming from the trailer which it would with the solar charge controller if it is doing a bulk charge on the batteries (absorption charge would only be 13.6V so may not trigger the issue). Also I suspect it took a bit of battery drain from the fridge for the voltage on the trailer batteries to drop back down and hence the delay between turning off the solar charge controller and the trailer brakes coming back.

I had a couple of instances on the return trip where I got the same message again briefly about trailer being disconnected after getting gas, but it lasted only briefly and the trailer brakes were working.

I am considering the idea of putting a diode in there as suggested earlier in this thread so I can still have the solar panels charging while I am driving as it's nice to have the batteries fully charged when you get to your destination.

However, I also have been getting a strange error message from the Lippert One Control app as my trailer as the Lippert ABS brake controller system in it. Initially I thought perhaps these were related, but now I am thinking they are potentially not related at all. Has anyone else seen this message?

View attachment 49505

Strangely I get this message from the One Control app on my phone while the trailer is out in the driveway attached to shore power (ie: batteries are charging) and I get no other information in the app. Just the notification that pops up on the phone. The diagnostics screen just sits and spins so I cannot get any more information about what this means.

What truck do you have?

 

[bossman2024]

What truck do you have?

2024 GMC Sierra 2500HD AT4

 

[msutoad]

I just ran in to this exact same issue on my way back from Miami this past weekend and Grand Design support told me to disconnect the solar. When the issue happened I had ZERO trailer brakes (thankfully it's flat as tack in Miami!). Turning off the solar initially did not fix the issue, and we started the process of finding a mobile service tech when the trailer brakes came back. I suspect it is the voltage issue as I have Lithium batteries in my trailer and the Grand Design tech said the brake controller gets confused if it sees > 14V coming from the trailer which it would with the solar charge controller if it is doing a bulk charge on the batteries (absorption charge would only be 13.6V so may not trigger the issue). Also I suspect it took a bit of battery drain from the fridge for the voltage on the trailer batteries to drop back down and hence the delay between turning off the solar charge controller and the trailer brakes coming back.

I had a couple of instances on the return trip where I got the same message again briefly about trailer being disconnected after getting gas, but it lasted only briefly and the trailer brakes were working.

I am considering the idea of putting a diode in there as suggested earlier in this thread so I can still have the solar panels charging while I am driving as it's nice to have the batteries fully charged when you get to your destination.

However, I also have been getting a strange error message from the Lippert One Control app as my trailer as the Lippert ABS brake controller system in it. Initially I thought perhaps these were related, but now I am thinking they are potentially not related at all. Has anyone else seen this message?

View attachment 49505

Strangely I get this message from the One Control app on my phone while the trailer is out in the driveway attached to shore power (ie: batteries are charging) and I get no other information in the app. Just the notification that pops up on the phone. The diagnostics screen just sits and spins so I cannot get any more information about what this means.

I have seen issue but never had the trailer disconnect on my truck.

after debugging my abs with Lippert and they are sending me a new brake abs controller for the trailer.
fyi

 

[bossman2024]

So they sent you a new ABS controller and it fixed the problem, or you have not gotten it yet?

I do have an open ticket with them about this ABS error and I suspect maybe mine needs to be replaced also. But I am staring to think the ABS error and the trailer disconnect issue are entirely different things. Apparently there is a fix GM can do for the trucks to fix the disconnect issue as this guy got his truck fixed and it went away:

https://www.youtube.com/watch?v=s-_SfT4teJc