2021 GMC SIERRA 1500 Complaints

It started year and a half ago involving my tailgate. The buttons to operate by upper and lower tailgate failed to operate on the rear of the truck, but cab button and remote button would open the full tailgate. Returned truck to dealer and they replaced the rear control. It worked for approximate 4 or 5 months the the total tailgate button failed, half tailgate button worked no problem. About 6 mths ago I went to drive to work and hit a bump felt like something bounced but really didn't think of tailgate being open. Drove on interstate for 7 miles at speed of 70 to 75 mph. I had my structural firefighting equip in the bed. Stopped at a drive thru for coffee then drove 5 miles to other side of town to my workplace put truck in reverse and my camera showed the ground, my tailgate was open. Thank goodness nothing fell out of the bed. 2-3 days later left for work, hit bump and felt the rattle in the rear again, stopped and tailgate down, closed tailgate and it opened again immediate after closing. This has occurred numerous times, now the half gate now unmatched along with entire tailgate and opens hitting hitch, scratched paint off. Thought it was me hitting keys in my pocket but continued to occur with key in cab. My mileage warranty passed so I was waiting to get some extra cash to fix the tailgate latches. Have not seen any recalls for GMC sierra 1500 denali, thought I would file a "complaint".

I purchased this vehicle used with approx 16k miles on it. Not long after getting it - as I was driving it started dinging and then would shut off. Sometimes I’m in the fast lane going 75Mph and it’ll just shut off. The dealership can’t get it to repeat itself. They said they’ve heard of it happening before but it throws different codes. There’s no rhyme or reason to causing it to shut off, but here lately I don’t even get the warning bell. It just dies on me. As soon as i shift it to neutral and press start it’ll restart instantly. But it’s scary nonetheless, and causes me to drop speed instantly and poses a safety risk especially when I have semi’s or other vehicles close behind.

The Flex Tailgate has on multiple occasions has malfunctioned in cold temperatures. I have had instances where I can get it open when I have vital supplies in the bed of my truck because of the Tonneau Cover being on (I have a hard cover made for this truck) and the tailgate malfunctioning. I have also had an instance where my tailgate opened (after clicking shut) while driving without the notification coming up on my dash. I could've been held liable if my equipment fell out and caused an accident. Moral of the story this truck as a lot of issues when temps are below freezing even after being warmed up for 15 minutes or longer. I wouldn't recommend this truck based on the function of the Flex Tailgate. I would prefer a classic a handle and less tech now that I have seen it fail so many times.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the brakes seized, and the service brakes warning light illuminated. Additionally, the contact stated that the vehicle jerked forward. The vehicle was driven to the residence and parked. The contact stated that the vehicle was turned off; however, the service brakes warning light remained illuminated. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 34,500.

My 2021 GMC 1/2 Serria SLT 4x4 Crew Cab short bed, V-8 Gas engine with Automatic Transmission. I bought this pickup used with apprx. 41k miles on it. I had it about 2 months when I went out to start it and the battery was completely discharged, it would not even click or any lights come on. I hooked it up to a battery charger and got it started, took it to a shop and had the battery and alternator check which both were ok. Drove back home and went out the next morning and the battery was completely drained again, got it started and went an put in a new battery. 16 days later it did the same thing this time it smelled like wires burning when I opened the hood. Called the dealer I bought it from and they put it on a diagnostic machine for over 3 hours could not find anything. Then next morning the battery was again completely drained. Got it started and took it to another shop to get it checked out and after almost 3 hours there they found nothing. Came back home an it sat for just over 40 hours and again the battery was completely drained. I could smell what I think is plastic or rubber when I opened the hood again. My main concern is that this may be a fire hazard and could not only burn up my pick up but my house as well. The check engine light has came on but goes off so I am at a complete loss on this and seems as if GM is not concerned either. I have tried contacting GM but so far nothing other than a note from GM Canada that I need to contact the GM USA, and again that is the only thing I have gotten from anyone. Perhaps this is just a odd thing, I don't know but I do know it is not a safe thing.

5 days after purchasing and While driving down the interstate at 80 mph, there was a loud clunk at the same time the back wheels locked up for a split second, long enough to burn the tires and throw everyone in the vehicle forward then the vehicle continued on. It happened three more times, we trailered it and brought it to the dealer. They said nothing is wrong with it. However, I was able to locate the previous owners who stated they'd been bringing it to several dealerships to have it taken care of for the past six months and every dealer said that nothing is wrong with it. But the same thing happened to them for six months. One mechanic in Idaho even replaced the motor trying to fix it and it still continued. The dealer I purchased from never mentioned it having a new motor, and I pulled the Carfax report and it shows several times it was in the shop including the motor replacement, but the shop visits aren't detailed it just says maintenance. Several mechanics we've spoken with say it's in the transmission, drivetrain. But the dealer refuses to do anything unless it'll replicate when they test drive it. But they don't test drive it on the highway or for a long enough time. Multiple owners now in multiple states the same problem and no one will help. This could be a catastrophic incident if the roads had been a little wet or someone was close enough behind us when it happened it would have been a serious car accident, if not worse. I am not sure you can help but Im reaching out to everything that I can find.

"Service parking brake" "steering assist is reduced drive with care" comments showed up on screen…check engine light on, truck shaking/ vibrating completely as if wanting to turn off this all happened while driving on the road and randomly happened…please help..very Concerned

Tailgate opens when driving and when parked. I thought something must of hit the button on the dash the first time it happened but now it is constantly doing it on its own. It has damaged the hitch.

WHEN DRIVING HOME AFTER PICKING UP MY 2.5-YEAR-OLD AND 6-MONTH-OLD THE BREAKS FELT VERY ODD AND NOT RIGHT. WHEN I APPLIED THEM, IT FELT ROUGH TO APPLY AND THEN HEARD A NASTY SOUND COMING FROM THE REAR OFF TRUCK. I TOOK MY TRUCK IMMEDIATELY TOO THE DEALER AND JUST GOT THE PHONE CALL BACK THAT THE MASTER CYCLINDER FOR MY BRAKE SYSTEM NEEDS TO BE REPLACED. THIS VEHICLE HAS 22,500 MILES ON IT AND IT ALREADY NEEDS SOMETHING FIXED LIKE THIS IS PRETTY SCARY SINCE MY FRIEND JUST HAD IT HAPPEN TO THEM AND THEY GOT IN A MAJOR CAR ACCIDENT. THANK GOD I DIDNT HAVE TO PUT MY FAMILY THROUGH THAT. HAVING A BREAK FAILURE IS SOMETHING NOONE WANTS AND NOT WHEN THE VEHICLE IS PRETTY MUCH BRAND NEW STILL. THE DEALER HAS CONFIRMED THAT THIS IS A VERY RARE CODE IN TERMS THEY USED TO BE HAPPENING. THERE WAS NO WARNING LIGHT OR ANYTHING IT JUST HAPPENED THEN AS I WAS TAKING IT UP TO THE DEALER, I GOT THE SERVICE BRAKE SYSTEM ALERT ON MY DASH.

After having simple oil and filter, and engine and cabin filter replaced at Alpine Buick GMC in Colorado Springs, CO, I received my vehicle back and noticed a complete difference in performance. It hesitates when accelerating, stays low in every gear, and bounces, and I mean bounces hard, when shifting gears, especially slowing down. When slowing down, as it shifts to the next lower gear, it almost pushes the truck forward against me pushing the breaks. Then, when feathering to accelerate slowly, it almost bounces back up to speed, hesitating until I let off the accelerator pedal a little, and it immediately shifts to about 1000 rpm in gear. I have to push really hard for it to go up a gear, and when it does, it has lost all power. My vehicle doesn’t run right anymore after my service appt. I have brought it to my hometown dealership and they say it runs fine and nothings wrong. But there is something wrong with it.