On [XXX], I was driving my truck on [XXX] through Phoenix, AZ. It was 5 days after I had purchased the vehicle and only had 250 miles on the odometer. I was in the left lane was traveling at approximately 75mph. Within the span of about 20 seconds, several lights on the dash annunciated and several messages including a message about a brake failure and steering assist failure and then the engine suddenly turned off. The steering seemed heavy and the brakes seemed less responsive. I was able to coast to a stop on the side of the road thanks to the help of a couple truckers who blocked traffic across multiple lanes. The truck was towed to the dealer and they told me the entire engine needed to be replaced. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

- North Pole, AK, USA

Tailgate releases on its own while parked, without the use of the switch. Tailgate released on its own with my trailer attached while parked on many occasions. The result of the Tailgate releasing caused damage to the upper section of the Tailgate, the "kicker speaker system" in the Tailgate and Tailgate switch located on the upper section of the Tailgate. There also have been multiple times when attaching the trailer that the Tailgate has released and struck me in the head. The Tailgate also fills with water during rain, and carwashes. The damage caused by the Tailgate releasing is a dent on the upper section of the multi-pro Tailgate and rust and malfunction of the " kicker speaker system " as well as the occasional hickey and headache on my head. The Tailgate has filled up with water since I purchased it new in December of 2020 which I believe has been electricly shorting the Tailgate switch/button releasing the Tailgate randomly. Due to my particular 2020 GMC Sierra 1500 AT4 CarbonPro having the " kicker speaker system " in my opinion makes the Tailgate so much heavier than one without it that it made the damages such as the dent in the face above the Tailgate switch much worse than trucks without it also causing more water to enter the Tailgate causing more damage to the switch and components of the " kicker speaker system ", such as the amp and buttons for it not to mention my head on several occasions.

- Covington, LA, USA

DEF Emissions warning and Engine Emissions warning lights suddenly appeared. DEF Emissions warning went on and off multiple times in the two days before bringing to a GMC service location. Informed that the DEF Tank heater failed, a known problem, but that they likely would not have a repair available for over a month and would not be covered by any warranty. The vehicle is now speed limited to unsafe speeds on highways while waiting for the repair.

- Jber, AK, USA

My truck 2020 gmc sierra 1500 AT4 denali is not working properly since July 2024. I took it to 2 different dealership to get a diagnostic and i finally ended doing the repairs for brake issues. I have been towed 6 or more times and almost experienced 2 car accidents since I drive the truck after the supposedly repairs where done but i ended stranded again with no brakes. The dealership has repair the truck 3 times but im still getting sevaral codes the fact that i had to pay out of pocket and have to deal with this and expose myself to danger and my family in driving a vehicle that is no safety condition its absurd. I call several times the recall GM hotline and i was told GMC 1500 are included in the recalls just not the AT4 and i have a family member with the same truck and same issues she ended up trading in the truck recently since she kept experiencing the same issues over and over again just like me.

- Houston, TX, USA

My brakes failed 2 times. One time I almost got into a horrible wreck with my daughter in the truck. "Brake system failure" " max speed 43mph" I have not had any brake work or anything done. The dealer is trying to charge me to replace the whole brake system when [XXX] this says to reprogram. Still waiting on gmc to tell me if it's covered under warranty. From my own research this has been a major problem for hundreds of people if not more. I could have died because of a faulty brake system or a bad software update. I need help with this and so do the countless other 2020 gm owners. There is a recall on the 2019 for the exact problem but not the 2020s. GM safety recall N192268090 please advise INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

- Zebulon, GA, USA

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at various speeds, the vehicle was stuck in gear. While driving there was an abnormal burning odor coming from the vehicle. The vehicle failed to start on several occasions. There were sparks from the passenger's side front seat. Several unknown warning lights were illuminated. The vehicle was taken to the local dealer, where it was diagnosed with electrical, transmission module, wiring harness, air alternator cooler, and exhaust system failures. The vehicle was repaired; however, the failure recurred. Additionally, while driving at undisclosed speeds, there was a failure with the vault meter. The OnStar system provided an error with the antilock braking system. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 44,000.

- Brighton, MI, USA

My wiring harness which affects all systems. I was on the Interstate when out of nowhere any and all warning lights came on. The power was cut and rapidly slowed down. I also pulled into traffic and the truck just lost power. The problem was confirmed by dealership. The vehicle was inspected by dealership and wiring harness was the issue. The issues appeared out of nowhere. All the warnings lights came on at once. There has been numerous issues with this part and it-??s even recognized by just.

- Folsom, LA, USA

The rear sliding window leaks water inside the cab every time it rains. With water getting into the cab the issue of mold has begun and that could be a serious factor to any children or adults that ride inside the cab of the truck. There is also rust issues that are notable under the rear seats of the vehicle. Water inside the cab can also interact negatively with any electrical components of the vehicle. I tried to get ahold of the dealer and they always say they don't have time to get my truck in. I have read that this has happened to other vehicles that are the same year and model and they just fix it with caulk which does not seem appropriate for a almost new vehicle. The vehicle has not been inspected. There were no warning lamps prior to this issue. A possible symptom was that my back up camera stopped working for a day right after a rain.

- Corning, CA, USA

Back window frame crack led to water intrusion which flooded electric module controlling speedometer and adaptive settings. Extremely unsafe driving with faulty electrical components unknown to me. Insurance and Dealership told me this is a common GMC occurrence. Cost is near $10,000 to make truck drivable.

- Arbuckle, CA, USA

Electronic power steering stops working randomly which makes it nearly impossible to safely drive the vehicle. The strength needed to turn the vehicle is so great that the steering wheel elevation lock fails and the wheel slams to the lowest limit of travel. Problem started around 50,000 miles and was only a warning that went away as soon as I got in the truck again. However reappeared today and the steering went out this time. The GM dealer in Mexia Texas didn't know what was wrong, I am taking it to a dealer in Corsicana tomorrow. This is a known problem that GM has had in the past however my vehicle has no active recall to make my truck safe free of charge. This puts myself and other drivers at risk because there would be no way to rapidly maneuver the vehicle to avoid a colision.

- Mexia, TX, USA

We are unsure what happened that caused the issue. One day the dashboard just started giving us error messages, 3 of them to be specific. One says check turn signals, another says check trailer brake light and another something else about brakes or turn signals. (We have to dismiss them all before anything on the dash is viewable). This issue is causing the blinkers to blink fast as though the blinker lights need replaced and it happens when turning right or left. The alerts continue to give us error messages every few minutes, even after we have dismissed them all. We had the truck at a shop trying to figure out the issue and his guys spent hours and replaced things he thought were causing the issue but nothing fixed it. He referred us to take it to the dealership service shop for troubleshooting so we took it to the GMC dealer where we bought the truck. GMC has already spent hours, maybe 5-7 hours at $150 per hour, trying to figure out what's wrong and have been unable to find anything wrong. The truck is still at the GMC dealership shop but I can get pictures of the errors when we get it back.

- Blaine, MN, USA

Camera always stays on even when i am driving camera still on my dashboard

- Deming, NM, USA

I own a 2020 GMC Sierra 1500 4-Cyl, Turbo, 2.7 Liter with 20K miles and I owned the truck for almost 2 years. All of a sudden my vehicle started receiving multiple warning messages. While driving I stopped, and when traffic stopped in front of me the engine died all the lights were on warning messages on the dashboard started showing up. Electronic Stability Control, Antilock Braking System, ECM, reduced Engine Power, etc., and the brakes were hard to step on it and the steering wheel hard to turn, I took my foot off the brakes and pressed it again to start. It started but the check engine light was still on, this happened FOUR times already and THREE times while parked when I tried to start, after a few tries giving few minutes intervals, it will start with all the lights on and warning messages on the dashboard start showing up. Electronic Stability Control, Antilock Braking System, ECM, reduced Engine Power, etc., and the brakes were hard to step on it and the steering wheel hard to turn.

- Aventura, FL, USA

Normal driving conditions vehicle decelerated and warning lights and notification appeared. Warning were -??Service ECS-?? and -??Steering Assist is reduced Drive with care-??. Shut off vehicle for 30 minutes and warnings were no longer present and vehicle drove normally. Happened again 24 hours later. Received email notifications from GMC to arrive within one day. This was a know recall of the previous model year.

- Two Harbors, MN, USA

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving in the snow, the tire pressure and power steering warning lights illuminated. The vehicle was not diagnosed or repaired. The vehicle was taken to a dealer where it was confirmed that there were no recall or warranties that would cover the repairs for the warning lights. The failure mileage was 140,000.

- Rowlesburg, WV, USA

I have a lifters problem that the dealership takes more that three weeks to fixed without a loaner car, then i have electrical problems where the truck doesn't start at all without any warning and that's it's dangerous, never now where its going happen

- Fort Worth , TX, USA

Own a 2020 GMC Sierra AT4 with 13K miles and I owned the truck for 1 year. All of a sudden my vehicle started receiving multiple warning messages. Electronic Stability Control, Antilock Braking System, ECM, reduced Engine Power, etc. I see there was a recall for 2019 GMC Sierra's for the same issues. Why isn't 2020 GMC Sierra's not also part of that recall " It is ridiculous that a brand new truck has these types of serious issues affecting so many vehicles. Why is GMC allowed to continue to sell later model trucks after the 2019 recall with the exact same ESC and Anti-lock Braking system problems "

- Jessup, MD, USA

Two times while on the freeway the service parking brake and engine lights came on and starting braking. Could not drive over 20 mile an hour. Both times taking to dealer the lights where not on and they could not find anything wrong. I even have video of it happening.

- Pasadena, TX, USA

Bought 9-4-2020. On 9-4-2021 went start vehicle and no electrical power, battery dead. Will not hold charge to start. Brand new purchased at Morgan GMC in Shreveport Louisiana

- Jackson , MO, USA

Issue 1: Front left sensor(s), after a rain, car wash and now after an oil change, continuously vibrates the drivers seat and the red light warning stays lite indicating that an obstacle is located near the left front of the truck. This has happened on several occasions and after a time both indicator stop. Issue 2: When traveling on a freeway, twice now, the cruise control suddenly disengaged or decreased mileage, as if it had detected a vehicle in front of us. There was no vehicle within a quarter mile of us front or back, nor any vehicles on the side. No debris in the road either. Usually when the adaptive cruise is set and detects something in front the icons on the dash turn orange and starts to flash. That didn't happen, rather the cruise icon changed to blue in color and the truck slowed. This I would consider a safety risk. Both instances (December 2020 and April 2021) have been reported to a dealership and noted in a file. When the customer care person attempted to get malfunction codes, nothing appeared to be wrong with the vehicle.

- Lake City, FL, USA