2024 2500HD AT4 engine randomly shutting down

2500HDAT4 · September 8

I have a new 2024 Sierra 2500HD AT4 that I ordered and got in November of 2023. I have not had issues until May of this year, and the engine has started randomly shutting off(more information below). It happens with or without my fifth wheel attached, while stopping at a stop light, and now twice while towing down the highway. I have had it at one dealership that reported they had to reprogram the ECM. Now I took it to a different dealership to have them look into it, because I cannot keep putting my family in a truck that keeps shutting off the engine while towing our 13,000 pound RV.

When this happens, the engine shuts down, but all electronic components remain on and I cannot shut anything off or restart the engine. Three of these events have taken 10-15 minutes for all of the electronic components to shut down, and then I am able to restart the engine and everything is running again. I have pushed the onstar button every time that this has happened and had them run a limited diagnostic report related to the truck not being running. It displays an ECM code, TCM code, communication code, and sometimes faulty airbag code. However, once it is running again and they run codes it is all clear. It has happened while running and having the fifth wheel attached and in park, it has happened without the trailer attached when I made it to a stoplight and I sat there waiting for all of this to restart, and then most recently it has happened while pulling the trailer on the highway. When the engine shutdown occurred on the highway, I had no brakes on the truck, but I had trailer brakes to slow me down. I again called onstar and had them run diagnostics. I immediately called my GM dealership where I bought the truck. I cannot praise this dealership enough for how they took care of me and my family! However, I am torn on what to do. Do i trade it for a different one, as everyone seems to not know what is going on? In the state of purchase, the lemon law states that manufacturers have three attempts to fix life threatening issues before it is considered a lemon. I don't know if I want to tempt allowing it to happen again before I pursue other options with regard to familial safety.

Has anyone else had this happen? If so, did you get a resolution? The current dealership has had it for a week now, and reportedly been on the phone a couple times with GM engineers that are not sure what is happening.

I am torn between letting them try to fix the issue again, or pushing the lemon law aspect and getting another one. I am not willing to risk my family and feel unsafe in a vehicle that is designed to tow and handle what I have it doing.

Another JR · September 8

Ask the dealer if they checked all of your major ground connections from the battery to the body to verify they are not loose. It may not be the issue, but we have seen reports here of symptoms like that over the last 4 years where a loose main ground wite was the issue. In the past torquing on some appears to have been missed.

Edited September 8 by Another JR

Pryme · September 8

That would be unnerving especially with the huge rv in tow. Maybe consider finding a low mileage 23. I can’t help but notice the 24’s are just not as reliable based on all the problems posted on just this forum alone.

64BAwagon · September 8

Thats as serious an issue as you can have. The fact that you have Onstar data and a good explanation of the events will help them to pin point it. Its definitely repairable and in my opinion is likely a harness connector issue. you just need the right person willing to do the hard work of diagnostics. I understand that the changes to the 2025 trucks is to prevent issues like yours. I call BS on the technical folks not knowing what to do. You may (not saying for sure) just have a dealer that doesnt want to do the hard work. Based on the symptoms they should have been able to develop the diagnostics. I would try to get all communications in writing or make notes of every conversation.

Best of luck. Let us know what they come up with.

Edited September 8 by 64BAwagon

2500HDAT4 · September 9

Another JR- Thank you for the feedback. They have checked all the wires and reprogrammed all of the control modules, but I will make sure I question the ground. They are currently tracing all wires in the truck to make sure they are connected to the right points and that there are no shorts between modules.

Pryme- I have definitely considered doing just that. I'm also considering using this as the time that I might jump to a diesel engine.

64BAwagon- I will mention the harness connector concern to them. I also have a case open with the GM quality team, and they have been documenting every step of the way, as well as talking to the dealerships with me. We shall see what that result is. Worst case scenario, I push for the lemon law with an attorney.

ScathaTheWorm · Saturday at 07:45 AM

On 9/9/2024 at 4:55 AM, 2500HDAT4 said:

Another JR- Thank you for the feedback. They have checked all the wires and reprogrammed all of the control modules, but I will make sure I question the ground. They are currently tracing all wires in the truck to make sure they are connected to the right points and that there are no shorts between modules.

Pryme- I have definitely considered doing just that. I'm also considering using this as the time that I might jump to a diesel engine.

64BAwagon- I will mention the harness connector concern to them. I also have a case open with the GM quality team, and they have been documenting every step of the way, as well as talking to the dealerships with me. We shall see what that result is. Worst case scenario, I push for the lemon law with an attorney.

Try taking it to another dealership if these technicians cannot help you. Ask for a loaner HD (preferably gas) that can help you on your vacation so you will not get lost (assuming you have it on your insurance).

If yours is the diesel, then it probably is under a recall for the EGR.