2015 GMC Sierra 1500: transmission slipping

Filed Jun 26, 2025 · Transmission · AL

I am writing to formally submit a serious safety complaint regarding the transmission in my vehicle, which nearly caused a life-threatening accident while driving under normal conditions. While traveling on a two-lane rural highway, I was attempting to climb a steep hill when the transmission suddenly began to slip. My vehicle lost power mid-ascent, despite steady pressure on the gas pedal. The RPMs shot up erratically, but the vehicle failed to accelerate. As I began to crest the hill, the transmission completely disengaged, forcing my vehicle into a free-roll situation. The danger escalated quickly. As I started to descend the hill, I attempted to downshift to control my speed—but the transmission would not respond. It slipped again, and I was essentially coasting with no engine braking. An 18-wheeler was behind me, approaching fast. I could see it barreling toward me in my rearview mirror, and I had nowhere to go. With the road shoulder too narrow and no pull-off in sight, I had to veer dangerously close to the edge to avoid being rear-ended. I truly believe that if the driver of the semi hadn’t taken evasive action, I would not be here to write this complaint today. This transmission failure is not only unacceptable—it is a critical safety issue. A vehicle should not lose all power and braking control during normal highway driving. This is not just an inconvenience or a performance issue. This is a defect that puts lives at risk. I am requesting that this transmission be investigated for an official recall. I have since learned that I am not the only one experiencing these symptoms, and it is only a matter of time before this defect causes a fatal accident. Please take immediate action to investigate this issue. I am willing to provide full documentation, diagnostic reports, and be available for further interviews if needed. Lives depend on it.

Filed Jun 20, 2025 · Driver assistance, Transmission · AL

I am reporting a critical issue with the transmission. The transmission frequently slips, hesitates, and jerks unexpectedly during acceleration and gear shifts. On multiple occasions, the vehicle has lost power or failed to respond while entering intersections, merging onto highways, or attempting to accelerate—posing a serious safety risk. The issue often occurs without warning and has worsened over time. Additionally, there are instances of harsh downshifting, delayed engagement from park to drive, and sudden lurching forward or backward, which could easily result in a collision. Despite visits to the dealership and complaints made, the issue has not been resolved, and I’ve learned that many other owners of this same model have reported nearly identical symptoms. This appears to be a systemic problem with the transmission system. Given the safety risk, especially in traffic and at high speeds, I strongly believe this defect warrants immediate investigation and a formal recall.

Filed Dec 15, 2024 · Transmission · FL

On 12/11/24 I had exited I95N, While traveling down the exit ramp I felt my truck buck, upon the light changing I went to accelerate and the truck transmission slipped and barely got into first gear. I again came to another traffic light and the transmission did the same thing. I put my hazard lights on and shifted through all the gears and finally I was able to get the truck moving. The following morning I brought the truck to my local mechanic and I was told I needed a new transmission, which is going to cost me $4400. About a year prior my daughter had a similar problem with her 2018 Chevy Silverado in which she had to replace the transmission valve body. With both of these occurrences the truck gives you no warnings and just stops driving and causes a real threat to safety.

Filed Aug 13, 2023 · Transmission · IL

Transmission was shuddering and slipping and then completely went out. Would not engage any of the gears. This happened while driving through the mountains without towing anything. My family and others on the mountain were at risk since the transmission was slipping out of gear and no safe place to pull over. It had to be towed to a dealer and they confirmed the transmission was toast and they replaced it, of course not under warranty. $800 tow bill and $6.893.98 to replace the transmission at a GM Dealer...Also, had to get a rental car ($318).

Filed May 9, 2023 · Transmission · MO

Vehicle has a history of hard shifting and jumping forward under certain conditions. In April 2019, while on the highway traveling about 65 mph, the vehicle slipped out of gear and do no longer be driven. No warnings were displayed prior to the incident. The dealer replaced the torque converter and repaired a broken transmission shaft under warranty. Hard shifting and jumping continued to occur, but the vehicle went without incident for another 4 years. Yesterday, 5/8/2023, the transmission went out again while driving around 35 mph. Vehicle is currently at dealer. My research has shown there is a class action lawsuit in 26 States for transmission issues for GMC vehicles between 2015-2019. the federal safety agency needs to take action and issue a recall. Losing a transmission while driving is dangerous.

Filed Apr 21, 2023 · Transmission · 30,000 miles · IL

The contact owns a 2015 GMC Sierra 1500. The contact stated that while shifting from drive (D) to park(P), the contact heard a loud clunking sound. Additionally, while driving and downshifting the contact heard the loud clunking sound. The contact also stated that while driving at an undisclosed speed, the transmission slipped while shifting from 1st to 2nd gear, and the vehicle failed to immediately accelerate. The contact stated that the failure occurred more during the winter months. The vehicle was taken to the local dealer who reprogrammed the TCM however, the failure persisted. The manufacturer was notified of the failure. The failure mileage was approximately 30,000.

Filed Aug 3, 2020 · Transmission · 98,750 miles · AR

While driving the transmission slipped while attempting to change gears. This caused the vehicle to be unresponsive and indicate a problem accelerating. This has been getting worse over the past several months and ended up leaving me in a very dangerous situation yesterday while driving.

Filed Jul 14, 2016 · Tires · 11,300 miles · TX

Tl* the contact owns a 2015 gmc sierra 1500 equipped with continental crosscontact lx 20 tires, size: p275/55/r20 (na). While driving 65 MPH, all the tires vibrated. The vehicle was taken to the dealer on multiple occasions where it was diagnosed that the tires were slipping off the rims and needed to be replaced. The tires were replaced numerous times, but the failure recurred. The manufacturer was notified of the failure. The tire manufacturer was not notified of the failure. The vehicle failure mileage was 11,300 and the vehicle failure mileage was 1,100.

Filed Nov 3, 2015 · Transmission, Visibility · 500 miles · MS

The transmission seems to slip or hesitate at takeoff. The running lights are too dim to see down the road.

Filed Sep 13, 2015 · Fuel system, Lights · 750 miles · GA

Driving my new 2015 gmc $52,000 gmc sierra, I noticed a distinct slipping/hesitation/general roughness when accelerating from a dead stop. The truck seemed to either have a transmission or engine problem. Took it back to dealership for them to check, and they indicated that this was "normal" and it was just the "cylinder deactivation" feature performing as designed. I explained to them that cylinder deactivation only typically happens at highway speeds and especially not from a stand still. They stuck by their story and again stated this was normal. My son came to see me and drove my new truck. Of course the truck hesitated and slipped from a dead start. "what's wrong with your new truck dad?" he asked. I told him it was 'normal and he just rolled his eyes. This is not normal for every sierra that gmc makes with the 5.3 engine and 6 speed transmission would do this. I have read on numerous message boards and websites where this is an issue and gm needs to fix the problem. Also, the headlights are extremely dim and are barely usable. As others have stated, I can only see maybe 20-30 feet in front of me and not very bright at that.

Filed Jul 15, 2015 · Fuel system · 420 miles · CA

Since gm transmission software recall,truck is continually slipping in all gears,non and partial engagement of gearbox,very sloppy gear changes. This is a major safety issue,while operating on the freeways of southern california. Headlights are not within safety standards for lumens as per government headlight standards.this is a safety issue,dealership is at a loss,since gm has not given a fix or replacement for this problem.