GMC Sierra 3500 won't shift problems

Filed Aug 14, 2026 · Transmission · 71,000 miles · NV

The contact owns a 2022 GMC Sierra 3500. The contact stated that while driving 65 MPH and depressing the accelerator pedal, the vehicle hesitated before going into LIMP Mode. A dealer was contacted. No warning light was illuminated. The vehicle was towed to a dealer where it was diagnosed with transmission control valve failure. The vehicle was not repaired. The contact associated the failure with the federal safety agency Campaign Number: 24V797000 (POWER TRAIN); however, the VIN was not included in the recall. The manufacturer was notified of the failure and referred the contact to the federal safety agency Hotline to report the failure. The approximate failure mileage was 71,000.

Filed Jan 15, 2026 · Transmission · CO

I have a 2023 GMC Sierra HD3500 6.6 Duramax. February of 2025 the valve body failed after 23,000 miles. The failure happened when the transmission had an extremely hard shift at 55 mph and then went into 5 gear limp mode. Computer through code P0700 and P0747. The P0747 is the code that tells you the valve body failed. When I took the truck to the dealer, they would not let me take the truck home because of the high risk of the transmission locking up and causing bodily injury, aka crash. Since the valve body was back ordered, I was warmed that it may be a month to get a replacement and install it. I finally got the truck back after 33 days. To add to the frustration, GM would not give me a loaner truck. They would give me a loaner SUV but that did not have what I needed out of a vehicle.

Filed Jul 31, 2025 · Transmission · AZ

I'm reaching out for urgent help regarding my 2024 GMC AT4, which is currently at Newby Buick GMC in St. George, Utah, with a transmission failure that occurred on Saturday, [XXX]. While returning from a horse show in Ogden, Utah, the truck began to experience severe transmission issues near Santaquin, Utah, around 5:30 p.m. Just before reaching Santaquin, the truck jerked violently three times-so hard that I immediately checked the camera system inside my horse trailer to make sure one of my horses hadn't gone down. That's how intense the jolt was. I pulled into a gas station in Santaquin and called the dealership right away. At the time, I had three horses on board, it was nearly 100 degrees, and I was hauling a large living quarters horse trailer. The service manager was initially unavailable, but he returned my call shortly and advised me to continue driving to St. George at a steady speed if the truck could manage it. He also warned that it might go into limp mode, and in that case, I'd just be traveling very slowly. My husband was on standby in case he needed to meet me halfway, but I was hopeful that I could make it to at least Hurricane, Utah. I was able to access my GMC app on my phone at the time and confirmed to him that the transmission check light was on, and I was receiving a warning notification on the app indicating there was a transmission issue. I was able to limp the truck as far as Hurricane, where my husband met me. We unloaded the horses into stalls and took both trucks into St. George that night to drop the AT4 off at the dealership. On Monday morning, I contacted the dealership for an update and was informed that the issue was likely related to the transmission valve, and that the required part is on national back order-with an estimated delay of two months or more, but no confirmed ETA. This has been my first GMC diesel. I've always driven Dodge trucks. Over a year ago, I saw the new color GMC released and kept telling my husband how amazi INFORMATION REDACTED PURSUANT TO THE FREEDOM O

Filed Jul 9, 2025 · Transmission · 130,000 miles · UT

The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently went into LIMP Mode. There was no warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed that the transmission valve body sensor had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and referred the contact to the federal safety agency Hotline for assistance. The approximate failure mileage was 130,000.

Filed Jun 1, 2025 · Transmission · WA

Formal Complaint Against General Motors and Dealership – Ongoing Warranty Issue and Vehicle Inoperability To Whom It May Concern, I am writing to formally escalate a serious and unresolved issue regarding my vehicle, and the lack of meaningful action taken by both General Motors (GM) and an authorized dealership. My case is not isolated, it mirrors the experience of thousands of other GM customers facing the same known mechanical defect, as widely documented in online forums and communities. On [XXX], I purchased a used 2023 GMC Sierra 3500 Denali with approximately 25,000 miles from a dealership. The vehicle included the original factory warranty, and I also purchased an extended warranty for additional coverage. On [XXX], at approximately 26,000 miles, the truck unexpectedly entered limp mode and the check engine light came on while I was driving with my children. Please note—this truck is equipped with the Allison Transmission, which is marketed as one of the most reliable transmissions available. I immediately took the vehicle to Blade Chevrolet in Mount Vernon WA, the nearest dealership, where it remained for nearly a week before a diagnostic was completed. I was informed by the lead mechanic, Jason Visten, that the issue was a failed valve body solenoid #1—a component he clearly identified as a known and widespread issue within GM’s system. Mr. Visten further stated that GM has not been responsive to the dealership's requests for this part, which is currently on national backorder with no estimated timeline for availability. I was even told this specific part is being built for new vehicle production and are being prioritized over parts needed for warranty repairs, leaving my truck unusable and indefinitely sidelined for up to a year per Blade Chevrolet. I contacted GM Customer Service directly and received the same generic response. Also worth mentioning I almost got rear ended cause of limp mode activation and transmission locked up. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA

Filed May 16, 2025 · Transmission · CO

Transmission issues 5/5/2025, bearly 15,000 miles on it, was excelerating from a stop heading down hill when rear tires locked up, engine downshifted, engine light and limp mode flashed across my screen. threw it into nutral and coasted to next signal and pulled into gas station back parking lot. No codes pulled. called dealer to share and they knew exactly what was wrong with transmition value body problem. but is my transmission ok? Towed to dealer, no fix in sight. 7th vehicle at dealer with same problem. Others been there for months waiting on same part. Thank God I wasn't towing anything, but now I have to pay for rental and they say they are waiting on parts??

Filed Apr 21, 2025 · Transmission · MS

Previous years of my truck with the Allison “branded” transmission have been reported to lock up while driving. From what I can gather there was a recall. Instead of fixing the issues with the transmission a program was installed to put the transmission in limp mode during the failure. My model, a 2023 apparently came with the limp mode feature already installed. When my transmission failed it took the truck out of gear and locked up for a moment before I could safely pull over.

Filed Feb 28, 2025 · Fuel system · OH

I was towing my 44'camper entering the highway and during excellration there was a loud bang and the truck shuddered no lights on the dash. Pulled over and did a visual check of the vehicle and did not see anything out of ordinary. Continued on our journey and during the the week noticed clunking noise when shifting into park and into drive with no camper. We shortened our trip and returned home with no futher incidents. Received recall letter from GM in December, called the dealer and was told Gm has not released my VIN number yet. Called twice in January 2025 and the software was done on February 20, 2025. Truck seems to run as it should. I use the truck for business and to tow my camper. The software is only a patch. My fear is I'm out traveling with my 44' camper and the truck goes into limp mode limiting to fifth gear. Then I have to get the truck towed home and the camper. I travel with 3 dogs too. GM has known about this issue and has failed to fix the problem leaving me and my family at risk of a serious accident. I can not work without my truck and GM does not care about me or my family. I have several camping trips scheduled for this year and I'm considering canceling them because I don't feel comfortable with the software update.

Filed Jul 24, 2024 · Transmission · MN

Transmission had a hard shift which jolted the truck switching gears to a lower one unexpectedly. It caused my body to jerk back. It happened 3 times. 2 were mild but the 3rd time was extreme. Always while accelerating. Average speed was about 50 mph when this occurred. Dealer has confirmed a failure of the transmission valve body. If the transmission were to be put in park while traveling, it could cause major accident and injuries. After the 3rd time the engine warning light came on and the truck went into limp mode.

Filed Jun 6, 2023 · Transmission · MD

Apparently a common issue. The TCM (Transmission Control Module) failed and the vehicle will not start or shift. Vehicle went into limp mode on highway while towing a trailer. Part availability unknown and on backorder for a year.