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Puppy Raiser · 02-07-2025, 08:07 AM

I know there is a bulletin on the problems with 2024 GMC losing brakes on 5th wheel while towing. The GMC dealer in Parker AZ refuses to acknowledge. Now in Lake Havasu, any suggestions of where to go for help.

d23haynes57 · 02-07-2025, 08:18 AM

My thoughts would be that the brakes overheated to the point of boiling the fluid out of the calipers and the system is now vapor locked. Try having a shop bleed the brakes and see if that restores them.

Sorry but maybe I missed something. Is the truck losing the brakes or the controller for the trailer brakes stops working?

Puppy Raiser · 02-07-2025, 08:33 AM

Thanks for your input.
The bulletin re this problem from GMC says the problem is the solar chargers and they know the problem and issued a bulletin saying the repair will be free if truck under warranty. But finding a dealer that will honor that is a problem.

Gooma · 02-07-2025, 08:40 AM

Solar charger on brakes??
Go to a brake shop and get your brakes fixed. Either your fifth wheel brakes are not adjusted properly, or you have overheated your truck brakes.
GET UM FIXED!

Skip426 · 02-07-2025, 08:49 AM

Is the issue that the brakes on the 5er quit working while you're towing ??

Factory brake controller ?

From the sounds of your post ; a solar charger on the 5er , interferes with the GMC brake controller .

Have you tried pulling the fuse on the solar charger while driving ?

Cumminsfan · 02-07-2025, 09:17 AM

"If you're experiencing brake issues with a GM truck while towing a trailer equipped with a solar charger, the likely cause is that the solar charger is pushing too much voltage back into the truck's system, causing the trailer brake module to shut down due to a voltage mismatch, essentially "disconnecting" the trailer brakes; this is a known issue with recent GM trucks, and the solution usually involves disabling the solar charger while towing or contacting your GM dealer to check for potential software updates or hardware fixes related to the trailer brake controller."

R.M.A · 02-07-2025, 09:23 AM

Quote:

Originally Posted by Puppy Raiser

Thanks for your input.
The bulletin re this problem from GMC says the problem is the solar chargers and they know the problem and issued a bulletin saying the repair will be free if truck under warranty. But finding a dealer that will honor that is a problem.

I have a feeling that NHTSA a known brake issue will be fixed for free regardless of warranty status.
Stinkin' crooks.

MtCamper · 02-08-2025, 08:03 AM

Sounds to me like a simple diode on the trucks charge circuit would prevent an overcharge from RV solar.

xc-mark · 02-08-2025, 08:18 AM

it's a KNOWN recall on most newer GM trucks. If the battery voltage in the RV is higher than the truck its locks out the rear trailer brake controller in your truck. the quick fix is to turn off the solar charger during travel. If your solar controller is programable just reduce the voltage to 13.7 volts so it still has the battery at full charge but not over the voltage where the trucks lock out.

The other cause is if your OEM brake controller see any type of fault with your trailer brakes. For example, your right to left trailer brake wires run inside the axle tube on most trailers, these wires get chafed and short to ground intermittently. this causes the brake controller to turn off. If your trailer brake has disk brakes with an electric hydraulic pump you may need to install a CAM. This CAM is a quick fix to make the resistance your truck brake control see a brake magnet resistance similar to what it would see if you had drum brakes.

https://hydrastarusa.com/collections...e-cam-381-7073

traveldawg · 02-08-2025, 05:45 PM

Quote:

Originally Posted by Puppy Raiser

I know there is a bulletin on the problems with 2024 GMC losing brakes on 5th wheel while towing. The GMC dealer in Parker AZ refuses to acknowledge. Now in Lake Havasu, any suggestions of where to go for help.

There is a bulletin. I recommended it to a friend months ago. He had to insist that the dealer perform the action described in the bulletin. I don't remember that action tho.

Seems you need to insist on getting the work done. Maybe calling GM's 800 number and opening a case might sway the dealer.

TampaDave · 02-18-2025, 02:39 AM

Seems to me there's an incompatibility between the 2024 GM brake controller and certain electric -over-hydraulic brake systems. If you happen to have Hydrastar system, they have a module you can wire in that supposedly fixes it ($50). I'll let ya know in a week if that works.

Frankly I dunno that the stock GM controller is anything to jump up and down about, in the end I'm probably gonna get an aftermarket controller. Which I expect to work better, have more functions, and may even be easier on the brakes themselves

xc-mark · 02-18-2025, 12:22 PM

Quote:

Originally Posted by TampaDave

Seems to me there's an incompatibility between the 2024 GM brake controller and certain electric -over-hydraulic brake systems. If you happen to have Hydrastar system, they have a module you can wire in that supposedly fixes it ($50). I'll let ya know in a week if that works.

Frankly I dunno that the stock GM controller is anything to jump up and down about, in the end I'm probably gonna get an aftermarket controller. Which I expect to work better, have more functions, and may even be easier on the brakes themselves

Install the hydrostatic CAM, it should fix your truck . The Cam will work with any electric over Hydro system. The factory GM is connected to the computer and sensor add power based on brake applied pressure. Aftermarket system like the protogy use sensor that detect negative energy of the brakes. Basicly spitting hairs but the Aftermarket can't add brakes to the trailer as fast.

RVfixit · 02-18-2025, 12:33 PM

Quote:

Originally Posted by Puppy Raiser

I know there is a bulletin on the problems with 2024 GMC losing brakes on 5th wheel while towing. The GMC dealer in Parker AZ refuses to acknowledge. Now in Lake Havasu, any suggestions of where to go for help.

There is a GM Service Bulletin on this, #23-NA-113 that came out on June 28, 2023, copy attached. It does have to do with the solar panels charging the RV batteries to a higher voltage than the truck batteries causing a brake controller shut down.

23-NA-113 1..1.pdf

The bulletin has a temporary fix recommendation until GM can correct the issue.

Good Luck and Safe Travels!

jb882 · 02-18-2025, 12:38 PM

There is a recall on this issue, im shocked that they didn’t see it when they pull up your vin. print this page from the NHTSA and show it to the dealer.

https://static.nhtsa.gov/odi/tsbs/20...04804-0001.pdf

I had my 2024 done back in July. It did not 100% fix the issue for me which as mentioned in this thread i think its caused by the hydrostar brake actuator and the truck does not like it. I loose my brakes every once in a while now and the only way to get them back is to stop, power off the truck and they retire it and go. I have yet to install the cam module but will IF i keep this truck….

I also think blaming “solar” is complete and utter BS on GM’s part. My solar is 100% isolated from the brakes electrically. I have a 24v solar system and the brakes and generator start have their own small 12v battery that is isolated from the solar and mine still has problems.