2024 Brake controller Problems

M3rlin · August 26, 2023

FIX IS COMING FROM GM! 8/26/2023 - Our FSA will be installing a component on my 2024 3500 this week and testing it with my LQ trailer (no solar charger, just aux batteries on trailer) at our dealership. Will update with the results. I can say that I had zero issues of dropping the trailer brakes when the Hydrastar CAM was working properly on my 850 mile trip to Tennesse in July. The CAM wire was cut at some point under the truck and the issues with the trailer brakes came back. Pretty certain GM is on the right path with the part we are asking this week. Fingers crossed!!!

Salzette · August 26, 2023

19 hours ago, MTU Alum said:

There should be a service part available next week once they publish the bulletin.

#iworkforGM

Will this be something all the 2024 should need for rv towing? Curious as we just picked up the new truck today and obviously haven’t towed the camper to see if we have the same problem. But we have fall camping plans once we get some miles on it…

Edited August 26, 2023 by Salzette
Spell

MTU Alum · August 27, 2023

6 hours ago, Salzette said:

Will this be something all the 2024 should need for rv towing? Curious as we just picked up the new truck today and obviously haven’t towed the camper to see if we have the same problem. But we have fall camping plans once we get some miles on it…

Unless you are charging your trailer batteries going down the road, the likelihood of needing this is low. There are some issues with hydrastar EOH brakes that maybe related as well.

lurker_007 · August 27, 2023

Hopefully the fix is out soon. This weekend we went on a 200 mile trip to North Ga and pulled it home today another 200 miles. With our trailer battery disconnected we had zero connection messages or brake malfunctions. The diode came in while I was out of town so I may wire that up this week if I get a chance. For anyone curious, I ordered the RoadMaster RM690 from Amazon. Should work for this issue if the 12v back feeding is the correct cause of the problems. Will update whenever I can.

UWSkier · August 28, 2023

My truck goes in on Tuesday for service. Hoping they have the bulletin published by then so I can point the service director to that. Also need them to figure out why any trailer I plug in says the running lights don't work, and the running lights are always on. Will update what I hear.

lurker_007 · August 30, 2023

My tech heard back from an engineer today. Looks like the current remedy is to replace the brake control module with the old version found in the pre 2024 trucks. My tech ordered one based on the old part number and is hoping that gm doesn’t send the new version since it’s vin specific. Will update once I know more. Thanks.

M3rlin · August 30, 2023

UPDATE 8/30/2023: I have my truck and trailer back. I’ve driven 40 miles with it and had zero disconnects. The tech had my truck and trailer for an entire day. He drove it all over the place with zero disconnects. A service bulletin should be coming out shortly. They replaced the TBCM with an older TBCM. They are VIIN matched and can be difficult to order under warranty for the 2024 when they don’t match with the VIIN.

Edited August 30, 2023 by M3rlin

UWSkier · August 30, 2023

I have an appt in mid Sept to address this. They didn't have the techs available yesterday to check this out on my truck. If the solution is to install the 2023 braking module, that's fine, as long as that doesn't screw up other things.

I think I'm still going to put the diode in place. I don't see a need to ever back-feed voltage into the truck.

jonpc · September 2, 2023

I installed the diode inline with the trailer plug and it worked perfectly. Did not receive a single check trailer wiring message on a 400+ mile drive.

On previous drives the message would occur as soon as the trailer batteries charged via solar and converter. I found that if I turned on everything in the trailer, it would eat up battery and would be a temporary fix until the solar generated more then the usage. I have 600 watts of solar so it would normally throw the error after 30 minutes of sunlight. With the diode installed, I had no issues.

I will see if gmc will swap the brake controller to the 2023 version during next service. For now this is a viable solution for reliable brakes.

ssgballistics · September 2, 2023

I apologize if this is a stupid question. Did you guys install the diode on the trailer brake wire or the hot lead? I towed my travel trailer with my new truck for the first time a couple of days ago. I got several messages for trailer brakes. I’ve never had an issue with any other truck. After reading this thread, seems like a diode may be a simple fix.

jonpc · September 3, 2023

The diode was installed on the 12v hot wire. The brake cable is left untouched.

On my rig the wire was black (12 v).

Did another 300 miles today and did notice that the truck gives a message that the gain control setting was not saved when the truck was started. I am guessing the diode may be interfering with the saved settings of the gain control. However the gain 4.5 was still set whenever the error message shows. I manually engage the trailer brakes before moving and still have had no issues before the message.

UWSkier · September 3, 2023

16 hours ago, jonpc said:

The diode was installed on the 12v hot wire. The brake cable is left untouched.

On my rig the wire was black (12 v).

Did another 300 miles today and did notice that the truck gives a message that the gain control setting was not saved when the truck was started. I am guessing the diode may be interfering with the saved settings of the gain control. However the gain 4.5 was still set whenever the error message shows. I manually engage the trailer brakes before moving and still have had no issues before the message.

I've seen that message pop up sporadically on my trailer too both with and without the generator running. I'm not certain it's related to the diode. Unless you're saying you get that message every time.

ChrisWithTheCanyon · September 4, 2023

On 7/8/2023 at 7:27 AM, Kyleb100 said:

Super thankful to land on this forum. This was my EXACT issue with my new 2023 GMC Canyon towing my RV that I've had for 4 years (bought brand new). I know 100% that it is not a wiring issue as I just dropped a new axle in (personal preference for an upgrade), have new brakes and ran all new wiring and tested all wires out myself, validated brakes worked and went for my first test trip and got the message over and over and over. Long story short and after doing all the simple things first... I ran across this thread. I already had a disconnect for my solar in place, simply disconnected and magically everything worked flawlessly with no more errors. Ended up going 200 miles with no messages at all.

After getting home, I ended up putting a disconnect in for the power lead coming from the truck to the trailer as I really don't want it trickle charging my battery system anyway and there is nothing for it to power either. My emergency break away brake is connected to the RV batteries and no need for powering from the tow vehicle. Did another drive today with the solar ON and the power lead disconnect in the OFF position. Worked flawlessly.

Super frustrated that the built in controller has this problem but again - thankful for this forum to help diagnose and get it fixed up so that it is not a safety issue while on the road. I'm going to turn this into my local shop too and see what happens.

UWSkier · September 4, 2023

14 hours ago, ChrisWithTheCanyon said:

Super thankful to land on this forum. This was my EXACT issue with my new 2023 GMC Canyon towing my RV that I've had for 4 years (bought brand new). I know 100% that it is not a wiring issue as I just dropped a new axle in (personal preference for an upgrade), have new brakes and ran all new wiring and tested all wires out myself, validated brakes worked and went for my first test trip and got the message over and over and over. Long story short and after doing all the simple things first... I ran across this thread. I already had a disconnect for my solar in place, simply disconnected and magically everything worked flawlessly with no more errors. Ended up going 200 miles with no messages at all.

After getting home, I ended up putting a disconnect in for the power lead coming from the truck to the trailer as I really don't want it trickle charging my battery system anyway and there is nothing for it to power either. My emergency break away brake is connected to the RV batteries and no need for powering from the tow vehicle. Did another drive today with the solar ON and the power lead disconnect in the OFF position. Worked flawlessly.

Super frustrated that the built in controller has this problem but again - thankful for this forum to help diagnose and get it fixed up so that it is not a safety issue while on the road. I'm going to turn this into my local shop too and see what happens.

Might be a better idea to put in a diode instead of a disconnect. That way power can flow from the truck to the trailer but not back the other way. It will help keep your 12v system on the trailer charged and working if you forget to turn on your solar. Not sure what, if any, 12v loads you have when rolling down the road, but my trailer has a 12v fridge, so we like to keep our house battery in tip top shape.