2021 GMC Sierra 1500: harsh or hard shifting

Filed Oct 5, 2026 · Transmission · 38,000 miles · FL

The contact owns a 2021 GMC Sierra 1500. The contact stated that the transmission was previously replaced. The contact stated that 20,000 miles later, the vehicle started to experience erratic hard shifting while driving at various speeds, and the vehicle failed to respond upon shifting into reverse(R). The vehicle was towed to the dealer, where the battery was replaced; however, the failure recurred. The contact received notification of the federal safety agency Campaign Number: 24V797000 (Power Train). The vehicle was towed back to the dealer, where it was determined that the transmission needed to be replaced. The contact was advised that the repair was not covered under the extended warranty coverage associated with the recall because the required DTC was not retrieved. The contact advised the dealer to complete the TCM software update under the recall, which would enable the generation of warning lights and DTC. After several attempts, the dealer informed the contact that the TCM software update was unsuccessful. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was notified of the failure by phone and email, a case was filed, and documents were sent to the manufacturer. The failure mileage was approximately 38,000.

Filed Sep 24, 2026 · Transmission · CA

I own a 2021 GMC Sierra 1500 AT4 with the 3.0L Duramax diesel. The vehicle developed severe transmission problems, including harsh/jerky shifting and a hard clunk when shifting into reverse. The vehicle was subsequently diagnosed with an internal transmission failure. The repair facility informed me that the transmission gears had failed and caused damage to the transmission and stated that the failure appeared to be related to a manufacturing issue. The repair facility also advised me to watch for a future recall because they believed this could be a widespread issue occurring in other vehicles. I am submitting this complaint so the failure can be documented and considered along with other reports of transmission failures involving this vehicle.NOTE FROM AUTOSHOP:TRANSMISSION FAILURE WAS DUE TO A MANUFACTURE DESIGN FLAW, NOT DUE TO THE CUSTOMER'S DRIVING HABITS. THE PUMP ORIGINAL DESIGN IS WITH SLANTED GEARS AND THE GEARS ARE FORCED AWAY FROM EACH OTHER AND PLACING TOO MUCH STRAIN THE BEARINGS ANI THE BEARING FAIL. AN UPDATE PERFORMED TO HAVE STRAIGHT CUT PUMP GEARS TO AVOID BEARING DAMAGE. CDF DRUM AND CENTER SUPPORT CHANGED TO UPDATED PARTS THAT ARE HEATED TREATED TO AVOID DAMAGE

Filed Jul 9, 2026 · Transmission · TX

transmission shuddering, harsh or delayed shifting, and erratic gear changes. The truck jerks really bad during each shift of the ten speeds. A vibration or shudder typically occurring at speeds between 25-65 mph under light throttle. Also makes a bad noise every times it’s shifting. I have no lights on the dash and the gmc app tells me everything is fine when clearly it’s not . I see there’s a recall for my year and make but for some reason my vin doesn’t fall in the category

Filed Jan 3, 2026 · Engine, Transmission · NC

I own a 2021 GMC Sierra 1500 equipped with the 6.2L L87 V8 engine and 10-speed transmission. The vehicle exhibits the following issues: Persistent lifter ticking noise audible from the driver-side wheel well, even when the engine is warm. Rough idle that is noticeable at stops and low-speed conditions. Transmission shifting problems, specifically harsh or delayed shifts when downshifting from 3rd to 2nd gear during deceleration. These symptoms raise concerns about potential lifter failure and transmission defects. I am aware of GM’s recall (25V‑274) and the federal safety agency Engineering Analysis EA25007, but my vehicle’s build date (January 2021) currently falls outside the official recall window. Given the similarity of symptoms to those under investigation, I believe my vehicle may be affected by the same defect. Safety Concern: The rough idle and shifting hesitation could lead to unexpected loss of power or unsafe driving conditions, especially during deceleration or merging. Request: Please include this complaint in EA25007 and consider expanding the recall to cover earlier builds. I am willing to provide service records, videos, and additional documentation upon request.

Filed May 19, 2025 · Transmission · AR

The transmissions in this as well as several other models of GM as well as Ford products with these transmissions are known to have major issues. My particular vehicle has major transmission shipping issues that started right around 90,000 miles or so. It started with a hard shift occasionally and has now progressed to a consistant hard shift, as well as a major shudder issue in the 35-45 mph range as well as the 65-75mph range ( when shifting into applicable gears) this has gotten worse over the last few weeks. These GM/Ford collaboration transmissions have been faulty from their inception and are well known to start malfunctioning in the 80-120,000 mile range. Please recall these transmissions so that consumers are not faced with thousands of dollars in repairs in vehicles that should last well beyond the short life span of the transmissions. I have been quoted 62-6500.00 for a replacement as there is no rebuilding these transmissions according to the mechanics I have consulted...(some have cited part availability issues as a reason). This has been a well reported problem with these vehicles/ transmissions for years now with many complaints and issues about the faulty transmissions. Just google it. I don't understand why theu have yet to be recalled.

Filed May 16, 2025 · Engine · NM

While the vehicle is traveling at highway speeds it is misfiring and sputtering, giving the feeling of a hard shift. When the vehicle is idling, the engine is sputtering like it’s going to shut off. If the truck were to shut down, as it seems to be trying to do, this could be deadly at highest speeds or intersections. The vehicle has been at a dealer since January 2025. They claimed to have fixed it but upon paying over $1200 and picking it up from the dealer, the problem persisted. We had to take it back to the dealer within 5 minutes of picking it with zero repairs and no estimated time of repairs ever since. No warning lights appeared at all.

Filed Apr 2, 2025 · Transmission · MI

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at 50 MPH, the transmission independently downshifted and the rear wheels seized. The contact stated that the rear wheels skidded. In addition, the contact noticed an abnormal clunking sound. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The dealer was made aware of the failure. The contact stated that the failure occurred immediately after the recall repair under the federal safety agency Campaign Number: 24V797000 (Power Train) was performed by the dealer. The manufacturer was not made aware of the failure. The failure mileage was unknown.

Filed Feb 25, 2025 · Electrical · 60,129 miles · ID

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the transmission slammed into gear and the rear wheels locked up. In addition, the vehicle decelerated independently. The vehicle was driven to the shoulder of the road and turned off. The vehicle was restarted, and the contact noticed that the vehicle was independently reset. The vehicle was taken to the dealer where it was diagnosed with a failed wiring harness. The contact was informed that the wiring harness needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was filed. The contact was advised to contact the federal safety agency Hotline and report the failure. The failure mileage was approximately 60,129.

Filed Feb 4, 2025 · Engine, Suspension · 38,000 miles · MI

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal clunking sound coming from the rear suspension. The check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the rear suspension. The vehicle was repaired, but the failure reoccurred 4,000 miles later. The contact stated that while reversing, the contact heard an abnormal clunking sound coming from the rear suspension. The contact also stated that there was also a strong antifreeze odor permeating the interior of the vehicle. The vehicle was taken back to the dealer, but not yet diagnosed. The vehicle was not repaired. The manufacturer was notified of the failure, and a case was opened. The failure mileage was 38,000.

Filed Jan 16, 2025 · Transmission · NM

Transmission has a hard shift when coming out of each gear. 2nd to 1st shifts hard and jolts entire vehicle a head. Feels like a slip or difficulty in shift.

Filed Dec 21, 2024 · Brakes, Engine · FL

I received a notice of a recall for a known problem with GMC transmissions. it is very well known that these transmissions lock up and cause problems with braking and can cause the vehicle to slide off the road when the tires lock up. it also causes hard shifting, which I have experienced. GMC said they will not fix the transmission, they instead will add a device to monitor the transmission, so when the transmission locks up and causes an accident, it will let me know that it was the transmissions fault!!! How is this legal? they will let me know that their transmission caused the accident after the fact? why not fix it? typical of government to do nothing about safety... and instead make laws that allow big corporations and government to make money off of peoples deaths!

Filed Jul 25, 2024 · Brakes · AZ

While towing a trailer in tow/haul mode on the highway traveling around 60mph, their was a strong downshift clunking sound. About 10 miles later, it happened again, except this time the brakes logged up and truck skid for about a full second and then trailer began fishtailing slightly. Check engine like P2C7A came on. Seems like brakes or transmission momentarily locked up.