Driving down highway at 60 mph and truck shut off. had to try to get it over to the shoulder to off the travel lane. Dealer found wire harness chaffed at front left shock tower ECM bracket. Several wires damaged, repaired and cleared codes. This could have been much worse had I been in heavy traffic and needed to cross additional lanes of traffic to park in a safe area. I had no power steering and limited space to park the truck. I called to police to have a car dispatched to park behind me so the truck could be loaded on a tow vehicle to bring it to the dealer. This could have been worse had my wife been driving.
2020 GMC Sierra 1500 driver assistance complaints
Page 2 of 2: complaints 11 to 27 of 27, newest first, as owners wrote them.
ADDITIONAL INFORMATION RE ODI 116346689: Tried to report to GM using 800‑462‑8782 provided by you. Agent would not accept ANY information that I tried to provide, including year/make /model and would not confirm or deny that the issue was known by them. Agent said that the dealer would report their inability to fix the issue directly to GM, and that I could not. I have no way of knowing if the dealer made this report to GM. Calling this number was an infuriating, complete waste of time.
The contact owns a 2020 GMC Sierra. The contact stated that while driving at speeds over 38 MPH, and the Lane Departure Warning System was activated the seat indicator did not vibrate or sound an alert as intended. The vehicle was taken to the dealer where the software was reset but the failure persisted. The manufacturer was not notified of the failure. The failure mileage was 47,000.
The contact owns a 2020 GMC Sierra 1500. The contact stated while reversing the vehicle, the rearview camera image failed to display as needed, and the radio was inoperable. The vehicle was taken to the dealer, but the cause of the failure could not be determined. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was opened. The failure mileage was approximately 3,500.
At 103,000 my 2020 AT4 5.3L V8 had a P0307 code thrown. Cylinder 7 misfire. Driving highway speeds, sudden loud pop and then the service engine light came on and automatic braking engaged, and the idle got extremely rough. Ended up being a bad lifter, bent rod, tore lobe off of the camshaft. Roughly 8,000 for the repair, new cam, new lifters, spark plugs and coil packs. Now only about 3,000 miles later, driving, sped up to pass on the interstate and another misfire, P0306 this time Cylinder 6. Same symptoms check engine light, automatic braking, rough idle. Seems to be another failed lifter and bent rod. Currently awaiting diagnostic for this second misfire issue. When speaking with the tow truck driver and the mechanic both mentioned a significant rise in cases like this. There is definitely something wrong with the design that the manufacturer needs to be help responsible for. I have less than a month ago replaced all the lifters only to have another one fail again.
On two separate occasions, while traveling at highway speeds with the adaptive cruise control system on, my truck randomly started braking hard as if it was sensing a vehicle or obstacle in front of me but my lane was completely clear. The most recent time, I was almost rear ended because of this issue.
Lifters Failed in November 2023 and had repaired major engine damage including 4 cylinders, cam shaft, lifters, gaskets etc. After major repair work done. Truck is now doing same exact thing in January 2024. The dealership is stating they will not look at the vehicle unless i buy a new battery. I asked them to try a used battery to see if that makes a difference. And then if it is the battery i will replace. I was hung up on after the technician doug Pedersen stated ill have a supervisor call you back.
ABS LIGHT LIMITED TO 43 MPH ESC system Steering assist reduced Service Trailer Brake System Engine light on
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 ?
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.
2020 gmc sierra slt VIN:[xxx] 15,700 miles. Braking system failure at about 45mph on highway 78 in loganville, ga approaching an intersection with red light, vehicle seemed to loose all power braking. I stood with all I could on the pedal, and turned to avoid rear ending stopped vehicles, running into middle of the intersection before it stopped; no accident ! Dealer is replacing master cylinder and booster braking system, along with computer system upgrade. My concern is the dealership and the federal safety agency is aware of this issue, yet no cease and desist driving directive has been issued ! Information redacted pursuant to the freedom of information act (foia), 5 u.s.c. 552(b)(6).
Within 3 months (<4000 miles) from purchase vehicle began sputtering with hesitation, and ticking noise from engine while in motion followed by multiple alerts posting on driver display. Vehicle displays loss of power, and struggles to keep up with traffic. Check engine light flashing followed by constantly staying on, service ESC system activated, service parking brake, and steering assist reduced drive with caution lights all activated during this episode. Dealer worked on vehicle engine ( and completed on or around 1/08/2021), and replaced lifters, and oil control valve. On 01/13/2021 noticed that vehicles lane keep assist is now working sporadically, will not activate consistently when vehicle veers off the properly marked lanes on high-way/roads, and inconsistently alerts driver while in motion. The lane keep assist is suppose to correct steering, but this does not happen consistently. The collision alert system does not activate or work correctly. Noticed while driving that vehicles in front are not detected correctly, and informs the driver they are within safe distance (green this suddenly changes to yellow). In addition when vehicles in front apply brake, the collision alert system does not alert as it is supposed to, it stays in green even at extremely close range. Safety mechanisms don't appear to work correctly, and detects items that are not present. Noticed that vehicle detects lanes even on unmarked roads, and the front pedestrian alert system activates sporadically even if no pedestrians are in front of vehicle while driving. Concerned about safety features leading to hazardous driving conditions.
The engine failed at 5100 miles and is currently being repaired by the dealership. I requested a new car replacement.
My 2020 gmc sierras brakes failed on may 22nd and ECM and now the engine and transmission are experiencing issues based on the onstar report.
Parked truck for one hour, engine off. Came back and upon startup, received multiple errors that power steering and ESC required dealer attention. Brake pedal would depress to floor. Gmc sierra 1500 elevation trim
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.
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.
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