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Trailer brake recall on 2024 HD Duramax diesel Denali

6.8K views 45 replies 20 participants last post by  Noe911  
#1 ·
Good morning everyone,

Wanted to respond to some questions and inquiries regarding our trailer break problem. Since purchasing the new truck in June 20 24, we have had nothing but issues with the computer disengaging the trailer brakes on our 43 foot RV trailer. The dealership gives us a runaround saying that the part is still on order due to Covid. Covid was over two years ago. I called Jim in Michigan yesterday and they advised me that the dealership had not even ordered the part. I’m going down in person today to have this discussion with the service manager. Other GM owners had their module fixed on their Denali. We have had no luck as of today.
 
#2 ·
I own a Chevy I bought from an out of town Chevy/GMC dealer. When my pickup goes to the dealer, it goes to an in town GMC dealer. GM doesn’t care. I’ve used this dealer for close to 30 years. It was a family owned dealership. They sold at the first of the year, and for me, they are on probation. So far the service writer and mechanic tech are still there. Those two leave, I leave.
 
#3 ·
Hey Duramax family, so I took my truck back into the dealership yesterday after discussing the issues with the service manager. The GMC dealership here in my area performed the recall and we towed our fifth wheel yesterday for 3 hours to go camping. So far so good, we had no trailer disconnect, and the trailer brakes worked the entire trip to our destination. I will be crossing my fingers and hope we have the same success on our way home Monday.
 
#6 ·
It's criminal and may be said to be actionable that the trailer brakes just "quit" working due to a software glitch or something else. A failsafe or at least a dumber default, call it a limp home mode, should have been built in. Any of the aftermarket controllers do not seem to be troubled by this. This is clearly a place where a critical system was overengineered and has introduced an undesirable complication and set of issues.
 
#8 ·
There is confusion likely. There is a recall on a sensor regarding brake fluid. There is no recall on the trailer brake problem as they have no fix for it. The dealers say we had no idea and it’s GMs problem. But there was a bulletin issued in Nov 23 about trailer brake prob. In July 2024 a memo was sent saying the trailer brakes were affected on some trucks most were at dealers or in transit to dealers. They were supposed to notify customers and order part for fix but ours was replaced 2times and it wasn’t fixed. We had truck 15 days and gave it back to them. We will be fighting it in court. Lemon law says they get one time to fix it when it is a safety issue. We were going on RV trip and went up/down Douglas Pass from Wy to Ut. (Over 8000ft). I’d like to see the GMC salesman pull the vehicle going downhill with 17k lbs behind with the trailer brake issues. I was on my imaginary brakes the whole way and imagined having that less than adequate truck careening off the mountain.
 
#10 ·
Just to get started I have a 2024 GMC 3500 Duramax Denali and we pull a 39' 17,000 lb 5th wheel. I have had the exact same problem with my trailer brakes. I had the recall with new part installed and left on a 6 week trip. We didn't get 5 miles down the road and lost our brakes on the trailer! I showed the shop foreman this forum to possibly give them some direction. Both trailer harnesses have been replaced (inside bed and bumper 7 pin hookups. I have hooked up to trailer and when going through my check on lights and brakes my turn signals have gone fast mode and message check signals. Unplug the trailer and signals have no issue. I told the dealer I am not taking the trailer out to see if the trailer brakes are working. I do not think that solar, battery on trailer as specifically states in the recall.


After reading through the posts I am getting concerned as what the fix is? We are going to take another HD off their lot and go hookup to our 5th wheel and I will post the results.
 
#11 ·
If any of you that are having problems have Electric Over Hydraulic brakes there may be a fix that GM won’t take care of. At least that’s what happened to me. GM replaced a couple of modules with zero success. I have HydraStar EOH brakes and they came up with a fix. They have a diode that can be spliced on the truck side of the trailer to stop the back feed problem. It worked like a champ.
Hank
 
#15 ·
So in reality, if you have 2024 GM HD truck and Hydrastar EOH on trailer, you need the fix for the brake wire installed on trailer and if you have solar on trailer, you may need a solution for the 12v power line. I have a 2023 and trailer has solar (only 45watt) and have not noticed a problem, but was aware that I may have to do something to keep solar charging from feeding back to truck causing an error.
 
#17 ·
Update:
I want to update my original post concerning 2024 Duramax 3500 Denali Crew Cab long wheel bed. This is an issue with GMC 2024 and 2025 HD models. The issue is the truck disconnecting my 17,000 lb 39ft 5th wheel's (DRV Mobile Suites) when you are traveling on the road. This appears to be a common problem with any trailer that has a power source i.e. battery, solar. The brakes are electric over hydraulic made by Hydrastar. After 3 months of going back and forth with GM, installing the recall fix for this problem which did not work. I met with engineer from GM, GM regional Service Mgr., dealership Shop foremen and Service Director at my dealership.

This meeting finally came up with a solution. A part that can be purchased from Hydrastar for $50.00 (part #381-7074). I spoke with the Hydrastars owner and chief electrical engineer, Wendell, for 45 minutes. He pulled no punches and is very frustrated with GM after dealing with them over this issue. One issue is the replacement part for the GM recall is not going to work. I had the recalled part installed so I can verify it is not going to work. Five miles down the road trailer brake disconnect warning light came on. Put the 5th wheel back in storage and back to the dealership and then replaced the wiring harness for the 7-pin outlet in the bed and it did not work.

Hydrastar is very confident this part will fix the problem. After splicing this part on to Hydrastar’s brake wiring, I took the trailer out for over 25 miles without the trailer brakes disconnecting We are going to increase our milage gradually since we have been burned 4 different times with this dangerous issue. It appears that GM is not accepting any responsibility over this issue.

What bothers me is that GM is aware of this problem, and it appears that GM is trying to blame everyone else but GM. If it wasn’t such a Dangerous issue I would not be so concerned. I have had an issue with my brand new 2020 which is the exact truck configuration as this 2024. I traded in a 2017 GMC Duramax with the same configuration (never any problem with 2017) and first time we went to leave with 5th wheel and the new 2020 GMC Duramax 3500 it was not compatible with lights and brakes. Two 1/2 months later and again having to get GM engineer down to TX, he brings an LED electrical adapter with him made by Curt part# 57003 which lets truck recognize trailer LED lights. GM was aware of this problem but ran us around for over 2 months and we could not use the 5th wheel.

I have had it with GM. I don’t say this lightly, but I will never buy another GM product again and I have never had anything but GM products all my life. Just in the last 7 years I bought 4 GMC vehicles.. I know no truck is perfect, but these problems are too dangerous to ignore
 
#21 ·
I had the same problem with my 2024 GMC 3500 this past summer. The dealership replaced the module and it did not help. I finally managed to speak with Wendell at HydraStar, got the diode, installed it on my fifth wheel and the problem was immediately remedied. 2 weeks later I went from IL to CO and back and not one error message. I didn’t have the problem with my 2022 GMC with the same fifth wheel trailer so GM obviously changed something. I don’t think that it had anything to do with the solar, it’s definitely the EOH brakes. Wendell at HydraStar is great. GM, not so much.
 
#22 ·
The trailer brake power module changed due to chip shortage. While the same specs were used, things are not always created equal.

The hydrastar fault and solar panel fault were both setting the same trouble code. There was a service bulletin telling dealers to replace module with this particular trouble code.

The hydrastar fault was hard to find and reproduce. It was somewhat dependent on driving style with applying the trucks brakes. After capturing data on it, hydrastar was providing some feedback through the electrical connection that other EOH suppliers don't.

GM worked with Hydrastar to supply a fix that could be quickly purchased. GM is working a fix but circuit board redesign takes longer then it would be acceptable. Sometimes things are as easy as they seem.
 
#23 ·
We have been going through this issue since early January. We had our 2024 Chev Silverado 2500 HD diesel in for service for the trailer brakes disconnected/connected/service trailer brake messages. After 3 days at dealer they couldn’t find anything. We already had the brake controller changed due to recall. We left the RV Park thinking it was fixed and about 50 miles out it did it again. We did disconnect the solar panel, but that didn’t help.
As we drove into our RV site at the next RV Park, (we are on a cross country 8 month trip) about 120 miles out, our left brakes seized.
RV Mobile mechanics said brakes and drum were shot and crumbling. They also checked the truck and it showed a faulty connector on the truck. We took it into the local Chev dealer and they found a faulty trailer brake switch and put a new one in. Today we were researching any NHTSA issues other than the recall of the controller and found NHTSA Bulletin No. 21-NA-155. This is about the possible cause to what we experienced. It references a manufacturer recommendation to make sure the correct OEM Pollak 7 way (trailer side) is installed part 12-706 or 12-702. Our trailer is only 2 months old and has Epicord 7 way.
The mobile mechanics are coming next week to install new brakes and drum along with installing the Pollak 7 way trailer plug.
GM was supposed to make sure this was communicated to service depts and customers.
We, too, plan to test drive before we drive any distance. We have been stranded here for 3 weeks but lucky this didn’t happen on the interstate. If we get the message again we are buying a RAM. This is maddening! We are planning to submit a complaint to NHTSA, Chevrolet and Alliance (RV).
I’ll post an update next week.
 
#31 ·
Well I hate to say this but I have a 2025 Silverado 3500HD and just returned from Pigeon Forge to High Springs Florida and trailer brakes stopped working 4 times. Each time i had to unplug the 7 pin and reconnect it to get trailer brakes to work. Not sure if Ill get the runaround or not at GM but I have an appointment next week. I do have solar and Lithium
 
#33 ·
The best that I can figure out having dealt with this situation for a year and a 1/2 is if you have a power source. I e battery or solar on your trailer with hydraulic over electric brakes you're going to have problems. I have stayed out of this recently because the way I solved, the issue is that I did install the diode from, the brake manufacturer of my fifth wheel and it appeared that it worked but I got so disgusted with GM who will not stand behind their product with this serious issue. I traded my 2024 HD with twelve thousand miles and for a brand new Ford F350 and have had no trailer issues.
 
#36 ·
I have a 2021 3500 LT Duramax that will do this intermittently, not all the time while towing, but does happen occasionally. My TT weighs 5100 pounds fully loaded so it's not as much of a concern like others towing much heavier but now it's got me thinking. The message on DIC says "Trailer Brake Disconnected " even though I didn't do anything.

Time to more research especially if I buy a heavier camper, which I was looking to do earlier this year, but didn't pull the trigger.
 
#44 ·
Well the dealers down here have never heard of this. So I am the only person in the entire world that this is happening to. Maybe if some one is killed because of no trailer brakes, maybe someone will pay attention. Maybe or just wipe it under the rug.