2024 Brake controller Problems

Tracker48 · May 18

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Edited May 18 by Tracker48

BuckWallace · June 4

So I finally had my dealer take care of this when I had my truck in to perform the tailgate recall, but when I got home I noticed the part number on the service invoice (85073615) is different than the 23306694 listed in the TSB. Can anyone who has had this fix done recently confirm the part number used? We have a trip coming up later this week so I'll find out for sure then, but I'm wondering if the dealer just replaced the module with another bad one.

Edit: I just did a bit more research and gmpartsdirect shows the 85073615 as replacing 23306694. I'm not sure if that is just the normal bad 2024 part showing as a replacement to the old 2023 and earlier part, or if this is the updated 2024 part used to fix the issue...

Tagging @newdude in case he knows.

Edited June 4 by BuckWallace

newdude · June 5

22 hours ago, BuckWallace said:

So I finally had my dealer take care of this when I had my truck in to perform the tailgate recall, but when I got home I noticed the part number on the service invoice (85073615) is different than the 23306694 listed in the TSB. Can anyone who has had this fix done recently confirm the part number used? We have a trip coming up later this week so I'll find out for sure then, but I'm wondering if the dealer just replaced the module with another bad one.

Edit: I just did a bit more research and gmpartsdirect shows the 85073615 as replacing 23306694. I'm not sure if that is just the normal bad 2024 part showing as a replacement to the old 2023 and earlier part, or if this is the updated 2024 part used to fix the issue...

Tagging @newdude in case he knows.

Numbers can change for numerous reasons. Supplier change, design change, etc. So 85073615 being the newest number, it was because of something like that occurring.

BuckWallace · June 5

20 minutes ago, newdude said:

Numbers can change for numerous reasons. Supplier change, design change, etc. So 85073615 being the newest number, it was because of something like that occurring.

Thanks, Dude. I understand part numbers changing—I was just wondering if the part they used was, in fact, the correct part (i.e. newer version of the part instructed to be used in the TSB), or if it is just the "bad" 2024 part they threw in again.

Mike Michaud · June 5

I'm having a heck of a time diagnosing my warning lights. Same issue as some folks. I'm towing a 5th wheel with my new 2024 GMC Denali Ultimate dually diesel. I get a "check trailer brake lamp" and an occasional "trailer brake disabled - service required" warning. I had the truck plug replaced, as well as the 5th wheel plug and it didn't clear the problem. The lights work. Now, after going through all this, I believe it is the brake controller module. The problem is intermittent, but I'm 4,500 miles from home! I am trying to find a GMC dealership that can help as I move along.

Capt Bob · June 5

1 hour ago, Mike Michaud said:

I'm having a heck of a time diagnosing my warning lights. Same issue as some folks. I'm towing a 5th wheel with my new 2024 GMC Denali Ultimate dually diesel. I get a "check trailer brake lamp" and an occasional "trailer brake disabled - service required" warning. I had the truck plug replaced, as well as the 5th wheel plug and it didn't clear the problem. The lights work. Now, after going through all this, I believe it is the brake controller module. The problem is intermittent, but I'm 4,500 miles from home! I am trying to find a GMC dealership that can help as I move along.

Do you have solar on your 5er?

BuckWallace · June 11

Just thought I'd report back regarding the 85073615 part number as a replacement for the 23306694 number listed in the TSB for this brake controller issue in case anyone gets this fix in the future. I just completed a 400 mile round trip towing with the solar still connected and had zero brake controller issues, so it appears as if this new part number is correct.

Rick_ · June 22

Does anyone except for me have the accessory trailer camera and have you used it since the brake controller update?

Mine worked fine before the update and now it will work until I touch the brakes and then the camera basically goes black and then hoses up the trailer/turn signal camera view with the big red box projected into the center screen. It's either a coincidence that the camera went on the fritz after the new brake controller or fixing one problem may have caused another...

Jbraz · July 3

I am having this issue as well. I have Solar chargers and Lithium batteries, so the battery voltage is definitely higher than the trucks. On a trip back from Disney I had a major tire blow out on my 5th wheel that blew through the floor of the trailer. Then an hour later a second one on the other side also causing damage. I had been having trailer wiring issues flashing through the trip and lost trailer brakes several times before all of this. I thought there must be an issue in the wiring if the trailer. I went to the repair shop today to pick it up and the trailer brakes didn't work, I tested before leaving. The trailer had been sitting on the lot for three weeks charging with solar panels and was completely topped off. I left the trailer with them to check the brakes assuming there was an issue as I had recently pulled a car haul trailer without any issues. The car hauler didn't have a battery and it worked great. Now after reading this I realize exactly what is happening, and I am very concerned that there hasn't been a recall. Many RV's are converting to lithium and for great reasons, they are fantastic batteries! So maybe GM is not really in touch with their user community, or research future trends in the market, or very concerned about their safety. A brake controller shouldn't fail or cutoff for a fault for any reason, especially when safety is involved. imagine this happening when going down a mountain, or approaching a traffic jam. Scary

bruceb58 · July 4

First thing I did on my trailer was disconnect the 12V going from the 7 pin to my trailer batteries. I use a DC to DC converter to charge my lithium batteries from my truck trough a seperate Anderson connector.

cloud dodger · August 8

Hello everyone - first time post. So I've been following this thread as I've been experiencing the brake disconnect issues while towing my 20,000 lb fifth wheel with my '24 GMC Sierra Denali 3500 DRW. I had the service bulletin accomplished on Monday at my local GMC dealership and the brake disconnect problems still occurred. I am going to try the diode fix and ordered a Roadmaster 690 diode. I understand the diode needs to be installed on the 12 volt connector to the 7-way plug which I believe is in the junction box under the kingpin. I have never done this kind of electrical work before so I need some assistance. The attached picture shows the wires in my junction box. I can see the 7 wires that go out to the 7-way plug. Do I find where the two 12 volt wires are connected and install the diode between? Which wire goes to the IN side of the diode & which to the OUT? Appreciate any comments from those of you who have done this fix already.

Big D junction box.HEIC

bruceb58 · August 8

4 hours ago, cloud dodger said:

Hello everyone - first time post. So I've been following this thread as I've been experiencing the brake disconnect issues while towing my 20,000 lb fifth wheel with my '24 GMC Sierra Denali 3500 DRW. I had the service bulletin accomplished on Monday at my local GMC dealership and the brake disconnect problems still occurred. I am going to try the diode fix and ordered a Roadmaster 690 diode. I understand the diode needs to be installed on the 12 volt connector to the 7-way plug which I believe is in the junction box under the kingpin. I have never done this kind of electrical work before so I need some assistance. The attached picture shows the wires in my junction box. I can see the 7 wires that go out to the 7-way plug. Do I find where the two 12 volt wires are connected and install the diode between? Which wire goes to the IN side of the diode & which to the OUT? Appreciate any comments from those of you who have done this fix already.

Big D junction box.HEIC 1.18 MB · 4 downloads

Just disconnect the 12V wire and see if it fixes the issue. You can either do it on the trailer side or the 7 pin connector side.

Next question...do you use the 12V line to charge the battery in the trailer?

Edited August 8 by bruceb58

cloud dodger · August 15

Thanks for the reply Bruce. I don't use the 12V line to exclusively charge the trailer battery. I plug into shore power at home or when I camp to charge the trailer battery. My '24 GMC 3500 Denali DRW truck got a new integrated trailer brake controller from the GMC service bulletin and the part number is 23306694. My understanding is that this controller is what was used on '23 trucks, but it works without problems. I towed my trailer a few days ago after the install for a test drive of 45 minutes and about 20 miles - no issues. So I hope this problem is fixed, but I'm going to keep the diode just in case. I'm still looking for help with how to install the diode. In the picture the 10 gauge black wire under my thumb is the 12V that goes to the 7-way pin. But it connects with three other wires with a twist connector. So how do I install the diode with those other wires all connected together? I have little experience with this kind of electrical issue.

Trailer wiring in junction box.HEIC

UWSkier · August 15

20 hours ago, cloud dodger said:

Thanks for the reply Bruce. I don't use the 12V line to exclusively charge the trailer battery. I plug into shore power at home or when I camp to charge the trailer battery. My '24 GMC 3500 Denali DRW truck got a new integrated trailer brake controller from the GMC service bulletin and the part number is 23306694. My understanding is that this controller is what was used on '23 trucks, but it works without problems. I towed my trailer a few days ago after the install for a test drive of 45 minutes and about 20 miles - no issues. So I hope this problem is fixed, but I'm going to keep the diode just in case. I'm still looking for help with how to install the diode. In the picture the 10 gauge black wire under my thumb is the 12V that goes to the 7-way pin. But it connects with three other wires with a twist connector. So how do I install the diode with those other wires all connected together? I have little experience with this kind of electrical issue.

Trailer wiring in junction box.HEIC 1.12 MB · 4 downloads

You install the diode between the truck and that wire junction. Those other wires are coming from your charge controller, your solar, etc. They all meet there to push charge to your battery. I put in a diode last year, and with the 2023 controller TSB fix, haven't had a singe brake issue since over 6000+ miles.

Doug Chi · August 29

Have any of these issues been resolved after the new trailer break module from GM has been replaced? We have a new 2024 Sierra 2500HD with NO solar and our breaks continue to fail multiple times while pulling our 5th wheel. We had the upgraded module #84857588 installed and it did NOT correct the problem. It’s gotten worse. We are battling our local GM service department with them telling us there is nothing else they can do for us.

August 28, 2024