Everything was fine for about 6 months after having purchased vehicle as new. Then I got warning lights asking me to both service the parking break and service ESC with a warning that driving would be compromised just over 60mph. I notified dealer who says they fixed the glitch but it happened again. The last time, most recently, I tried to start the truck the next day and all the warning lights came on. This was followed by a complete shut down. No engine, no lights - not even lock/unlock with key fob. It had to be towed. This is a 2020 vehicle and seems like it will strand me some place at the very least. Awful, expensive, and perhaps deadly dynamics here. GMC, get your act together. You owe us immediately. Provide the fix immediately or give me money back with no contest.

- Sierra Madre, CA, USA

My 2020 GMC Sierra brakes failed on May 22nd and ECM and now the engine and transmission are experiencing issues based on the onstar report.

- San Antonio, TX, USA

Electronic ABS brake failure with 73 miles on odometer while stopped at red light alarm chimes sounded and power brakes were lost. Warning lights on dash ABS brake failure multiple engine warning lights came on. Dealer service was puzzled needed to contact GM technical support. Final outcome they are replacing the electronic brake module.

- Kearny, NJ, USA

The contact owns a 2020 GMC Sierra. The contact stated that while driving at 25 mph, the system brake failure warning message illuminated on the instrument panel. Once the warning light illuminated, the contact experienced complete brake and steering failure. The contact was able to steer the vehicle into a curb to slow down the vehicle and avoid a possible collision with another vehicle. The contact stated that he had suffered pain to his left shoulder blade and left knee; however, he did not seek medical attention due to covid-19. After experiencing the failure, the contact had the vehicle towed to desert sun motors, Inc. (2600 N white sands blvd, alamogordo, nm 88310) where they cleared the system's computer and informed the contact that they found no defects with the vehicle. Upon return of the vehicle, he experienced another brake failure as the check engine light illuminated while driving at 55 mph. Due to the failure, the contact was forced to run a red light and drive up an incline in order to bring the vehicle to a complete stop. The vehicle was then towed shamaley Buick GMC (955 crockett St, el paso, tx 79922) where it remained in their possession. The manufacturer was notified of the failure and a field inspector was sent to inspect the vehicle. The contact stated that know brake failure codes were detected. The contact stated after the third failure the vehicle was towed to shamaley GMC where it was awaiting diagnosis. The vehicle had yet to be repaired. The failure mileage was unknown.

- Almogordo, NM, USA

Highway driving engine light started flashing, received codes on service ESC and service parking brake. Truck seemed to loose power transmission started shifting very hard, cruse disengaged, lane keep assist stopped working, brakes and steering seemed to act different. When ignition was turned off loud noises from under truck sounded like brakes releasing with loud clunking noise.

- Dadeville, AL, USA

The ABS system failed while driving down the road causing the brakes to lock up and caused the truck to spin out of control nearly crashing into another vehicle and jumping over the center divide into oncoming traffic.

- San Jose, CA, USA

I was going about 15 miles per hour when suddenly all these error codes started popping up, first "ESC malfunction" then trailer brake malfunction, stabilitrak, steering assist reduced, brake system fail, lighs just pop up I do feel like the truck looses some power feels more sluggish, I took it to dealership, they recalibrated the break system and stuff, it fixed the issue temporarily, but the lights keep coming back, sometimes I turn the truck on in the morning and lights are gone, then later on I get all the error codes again while driving it. It started 4 days after I purchased the truck and happens daily since.

- Tolleson, AZ, USA

2020 GMC 6.2 L V8 1500 4W Sierra denali. Bought yesterday new from dealership. Today, not even 120 miles and brakes malfunctioned. I started truck with GMC app. Got in car with my family and as I pulled out of parking stall pushing on brakes met extreme resistance and sluggishly came to a stop. I put truck in park. Shut off and turned back on. Brakes still not functioning. 'brakes' 'ABS' and icons for traction control and check engine lights were on. Again attempted to drive. Driving 20 mph would take greater than 50 yards to stop, with me, 220# athletic male applying full force. Warning message also appeared 'brake system failure max speed 62 mph'. no idea where 62 was formulated. Also some message about trailer brakes came on too. No trailer was attached. I shut truck off. 30 minutes later started, check engine light was only light on. Brakes worked normal. Was able to cautiously get 3 miles home. This is a potentially fatal flaw. Again this truck is straight off the dealers lot. Onstar sent email stating 'issue with antilock braking system, take to dealership within 7 days '. so brake failure is a major issue. But also a known brake issue and the computers say stay below 62 mph and get serviced within 7 days are just as worrisome. A braking issue should instruct don't drive and have towed thanks

- Overland Park, KS, USA

Vehicle was parked. Entered vehicle and turned on vehicle using interior start button. Vehicle was put in reverse and was baking when all break pressure disappeared and vehicle was rolling backward and came to a stop before striking another vehicle and child. Vehicle was placed in park and ESC failure, trailer brake failure, traction control failure, power steering failure and do not drive above 62 mhp alarmed on the dash. Vehicle was shut off and on 3 times and reset finally regained some break pressure but check engine light came N. vehicle was towed to trent GMC, new bern nc for service. Service told us it had a recall. I was unable to locate a recall for this issue. This could have ended very bad. I am not assured that the problem is fixed.

- Havelock, NC, USA

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at 52 mph, the brake pedal was depressed but was very firm. The park brake was activated but failed to effectively stop the vehicle. The vehicle was coasted to a parking lot and was put in park. The brake system failure light, the ABS and several other warning lights illuminated. The vehicle was towed to the baker Buick GMC of charleston dealer, located at 1621 savannah hwy, charleston, SC 29407) where the vehicle was kept for a diagnostic test. The manufacturer was made aware of the failure and stated that the failure was a known issue and referred the contact to the dealer. The vehicle was not repaired. The failure mileage was approximately 7,020. The VIN was not available.

- Charleston, SC, USA