3GKALMEV5ML3618602021 GMC TerrainSLE

Vacuum pump failure caused my brakes to lock up and almost caused me to wreck into another vehicle

Driving on the Garden state parkway on Sunday night June 28, 2026 I proceed to cross over the ratitan bridge. There was traffic as I was going down the bridge at 70 miles an hour. When I applied the brakes the car would not stop. I had two 6 years old in the backseat. I applied 2 feet to the brake pedal and it was like a rock and the car would not slow down. I thought I was going to crash. I had to steer and lane change several times to avoid hitting other cars. This has something to do with the driving assist braking system. I was scared to death. If this isn’t a safety concern nothing is. This should be a recall for GMC to fix because it’s an accident waiting to happen.

Formal Safety Complaint – 2021 GMC Terrain Brake Failure Vehicle: 2021 GMC Terrain Incident Location: Garden State Parkway (NJ) Speed: Approximately 65 mph Incident Description While driving northbound at highway speed, I attempted to change lanes and apply my brakes. When I pressed the brake pedal, it became completely rigid (rock hard) and failed to function. I had no ability to slow the vehicle using normal braking. At that moment, I was forced to: Navigate multiple emergency lane changes to avoid striking other vehicles Prepare for potential collision due to lack of braking control Apply extreme force with both feet on the brake pedal in an attempt to generate any slowing Eventually, I was able to steer the vehicle to the shoulder while exerting maximum pressure on the brake pedal. During the incident, a “Driving Assist Brake” message appeared on the dashboard, and the braking system has remained in this same compromised condition since. Safety Concerns The brake pedal became non-functional without warning The failure occurred at highway speed, creating an immediate life-threatening situation This was not a gradual degradation—this was a sudden, complete loss of braking capability The issue persisted after the vehicle was stopped Broader Concern I have since found multiple reports and videos of other GMC Terrain owners experiencing the exact same failure, suggesting a potential systemic or design-related issue. Given: The severity of braking system failure The apparent repeat nature of this issue The lack of an active recall addressing it I believe this represents a significant safety risk to GMC Terrain drivers and the public. Impact This incident caused: Immediate danger to my life and other drivers Extreme emotional distress Loss of confidence in the safety of the vehicle Requested Action I am requesting: A formal investigation into this braking failure Immediate inspection and repair of my vehicle at no cost Clarification from GMC regarding know

Automatic transmission solenoid control valve body got stuck open and ruined the whole transmission. This has been a reoccurring problem with these vehicles. Image is from a code read. Issue was confirmed by Gastorf Chevrolet, and an independent transmission shop.

The contact owns a 2021 GMC Terrain. The contact stated that while driving at various speeds, the vehicle hesitated while depressing the accelerator pedal, with a misfire coming from the engine. During the failure, the message "Engine Power Reduced" was displayed on the instrument panel. The vehicle was taken to a local dealer, and the contact was provided an estimate for a diagnostic test. The contact declined. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was unknown.

Vehicle went into reduce engine power mode and check engine light came on. Vehicle has just over 60,000 miles. Code is telling me I need a new turbo and being quoted 1,500-3,000. I have read so many people having the same issue with needing a new turbo just after 60,000 miles

The engine light came on while driving, saying “engine power reduced”. It barely accelerates, RPMs go over 5, it chugs when driving. Taken to an independent service center.

around chirstmas, Was driving on the highway and the car threw a "reduced engine power" warning and went into limp mode. Check engine light came on. Car asymptomatic prior. got the code pulled and it said turbocharger under boost. The next day the check engine light went out and car was running appropriately. Took the car on the highway again and the car threw the "reduced engine power" warning and went into limp mode again in the middle of freeway traffic. It is a safety concern due to the engine going into limp mode in the middle of high speed traffic. I easily couldve caused an accident putting both myself and others in danger by the engine cutting the power in the middle of the freeway. The check engine light only comes on while going at freeway speeds. The light will then go out overnight and come back on the next time i go back on the freeway at 70-80mph speeds. I have taken it to one shop which reported an oil leak coming from the turbo both inside and outside and that it needed to be replaced. I have read several different forums of other users of the same year, make, and model experiencing the same issue. the car is only a few years old and the likelihood of a turbocharger being bad is uncommon but a major safety concern considering this happened out of nowhere with no signs or symptoms leading up to this.

The contact owns a 2021 GMC Terrain. The contact received notification of NHTSA Campaign Number: 23V339000 (Child Seat); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The dealer was contacted and informed the contact that the vehicle would not be inspected or repaired. The manufacturer was made aware of the issue. The contact had not experienced a failure.

The contact owns a 2021 GMC Terrain. The contact stated that the transmission was previously replaced. The contact stated that upon starting the vehicle, the check engine warning light illuminated. The failure had occurred intermittently. Additionally, the contact stated that while driving approximately 15-20 MPH and depressing the accelerator pedal, the vehicle failed to respond for approximately 1 minute. The vehicle was taken to the Nissan dealer it was purchased several times. The dealer retrieved diagnostic trouble codes: P057C and P057E, and the brake pedal position sensor was replaced twice; however, the failure persisted. The Nissan dealer took the vehicle to a GM dealer, where the cause of the failure could not be determined. The vehicle was not repaired. The contact related the failure to TSB Number: PIT5994 (Diagnostic Tip for Reduced or Low Engine Power on Acceleration). The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 78,843.

Constantly have water leaking into spare tire compartment, back seat floors and passenger floor. Mold/mildew smell coming through vents. Have had drains lines cleaned out, and still recurring having this issue. Unknown where leak is coming from. This is a serious health risk.

Driving my vehicle with no warnings, messages, or symptoms on adaptive cruise control Sunday [XXX] on [XXX] in Michigan. I changed lanes into the right lane when the vehicle abruptly, without notification, and with force, caused braking that unexpectedly and dangerously slowed the vehicle then released braking before doing the same a moment later. Vehicle was pulled off the road onto the shoulder without an accident, thankfully nobody was behind because they would not have been able to stop in time before hitting my vehicle and I assume the brake lights weren't activated since I did not press the brake pedal either time the vehicle was abruptly slowed causing audible noise of traction loss due to skidding. Vehicle engine would function but parking brake remained active leaving vehicle unable to change gears and transmission warning showed on instrument panel. Vehicle towed to a Chevrolet dealer in Grayling, Michigan where it remains and would be available for inspection. Dealer shows transmission as the cause and in need of replacement. Vehicle has been maintained at GM shops since original ownership. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

First time I had problems with my 2021 Terrain I took it to victory GMC on 9/20/24. At the it had 45,000 miles. Every time I would drive and accelerate it would shake extremely bad in the floorboard. There was also transmission fluid leaking. I picked the car up on 9/27/2024 and was advised that both front axles were replaced, which corrected the shaking and the driver side axle seal was replaced, which was where the leak was coming from. this was covered under warranty but at 45,000 miles I should not have been already having axle problems or any type of leak. I dropped my car off again on May 5, 2025. When I called them the day I made the appointment I let them know I had a service transmission message show up and then go away, I told them it’s taking longer to kick into gear when I’m on the highway, I told them it revs up past 4 1/2 RPMS at times when it had not previously done this and it just sounded like the engine is working harder. I also told them I had a check engine line come on and go off and it was code P2271 which was an oxygen sensor code. I also told them when I had the oil changed. They told me there was a slight oil cooler leak starting. All this was supposedly addressed when I dropped it off to be serviced on 5/5/25. I was called on five 625 to pick up my vehicle notifying me that they found no issues. They were unable to verify concern concerning my check engine light. They said there was no oil cooler leaking, it was just slightly seeping, so not considered a leak. And they said no transmission concern operated as designed. Fast forward to May 9, 2025… I got in my car in the morning and once again the check engine light was on. I drove it straight to GMC and had them put the reader on it. The oxygen sensor code came on. The same code I told them about on the 5th that they said was fine on the 6th. I made an appointment once again to get this check engine light looked at although the check engine light is not on at the moment again.

Drive shaft on my GMC Terrain needs to be repaired according to my repair shop. I brought it in as it was vibrating on acceleration and other times frequently. I was told it was the “drive shaft” and the mechanic states they have had Equinox and GMC Terrains coming in for same issue. (Specifically my year Terrain) I looked up and found this recall # for this issue: N212343560. I was never notified and now have a very expensive repair bill which may or may not fix the issue.

The contact owns a 2021 GMC Terrain. The contact stated while driving at various speeds, the transmission erroneously shifted to the neutral, causing the vehicle to decelerate. After restarting the vehicle, the vehicle operated normally. During the failure, the message " Power Reduced" was displayed. The cause of the failure was not yet determined. The local dealer was notified of the failure. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was 36,000.

The contact owns a 2021 GMC Terrain. The contact stated while driving 5 MPH, the vehicle stalled. There was no warning light illuminated. The contact stated that the failure was like GM Product Safety Recall: N222372310 (Inadequate Fuel Pump Flow). The vehicle was towed to an independent mechanic, who determined that the fuel pump had malfunctioned and damaged the camshaft. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not contacted. The approximate failure mileage was 86,000.

I purchased the car August 2024, I have had it for 4 months and while driving down the road a large fuel tank pops up stating low fuel and the car comes to an abrupt stop.The 3x the gas tank was never low. Parking brake comes on and car doesn't not move. All lights on dash come one. It has done it 4 times and thankful each time I was in a 30 mph zone. If I was going 55 I am sure the result would have been bad. The car last did it on December 29, 2024 and has been in the dealership for 3 weeks now and they cannot fix it. I told them 3 days into my purchase I wanted a full refund and they denied me. ?? I had that right I am still fighting with them to take it back because one of these times I am going to get in a bad accident. I don't feel safe in the car and I told them each time.

The contact owned a 2021 GMC Terrain. The contact stated while the brake pedal was depressed, it was released and the vehicle suddenly accelerated aggressively. The contact attempted to avoid crashing into the vehicle in front and swerved however the front of the vehicle still impacted the vehicle in front. The air bags deployed upon impact. A police report was filed. The contact stated no medical attention was provided, but did suffer bruises from the air bag and seat belt. The vehicle was towed to an independent mechanic. The dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was not available.

When car has been unused for a period of time, the right rear brake makes noise when the car is moved. This happend in either forward or reverse. Even after driving for a short period of time, the noise is still evident. Under warrenty, I asked the dealership to resolve. They indicate this is an ongoing investigation by GM. I purchased the car new in July 2021. This problem has persisted since purchase. I have reported it multiple times to the dealer but they pass it off as GMs problem. In reviewing other similar complaints for the 2020 model, it was resolved by changing the brake pads to a different material. Surely GM can find a cure after 3 years since production.

The car has revved high rpm's since purchase, with multiple attempts to get it resolved . Since then, the steering wheel has jerked out of my hand's multiple times, unexpecting, causing the car to jerk while being stopped. The car has also not budged in the middle of traffic while being in drive and the pedal down to the floor until at least a 10 second delay and when doing so the screen that includes the radio, etc panel has completely blacked out and started twitching

I was in a in a 70 miles an hour highway accident and was hit in front driver side door, went up embankment and hit a tree then rolled backwards onto the highway. No airbags deployed.

When accelerating from a stop between 35-45 mph the steering wheel shakes and you feel a vibration coming from the front wheels. I thought the wheels were loose and were about to come off.

The contact owns a 2021 GMC Terrain. The contact stated upon pressing the Push to Start button, the vehicle failed to start after several attempts, and the battery drained. The vehicle was towed to the dealer, but the failure could not be duplicated. The contact stated that the vehicle restarted after a while. The check engine warning light was illuminated. The contact stated that the failure recurred intermittently. Additionally, the contact stated that the vehicle stalled while at a complete stop at a traffic light. The contact also stated that the vehicle stalled while driving on two separate occasions. The contact was able to veer to the side of the road. On one occasion, the vehicle restarted after several attempts and was driven to the dealer; however, on the other occasion, the vehicle failed to restart and was towed to the dealer. The dealer diagnosed the vehicle but could not determine the cause of the failure. The vehicle was taken to an independent mechanic, where it was diagnosed that the fuel pump control module needed to be replaced. The vehicle was repaired; however, the failure persisted. The contact related the failure to NHTSA Campaign Number: 23V013000 (Fuel System, Gasoline); however, the VIN was not included. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 25,000.

Automatic Emergency brakes have unnecessarily or prematurely activated on 2 separate occasions causing my car to stop very abruptly which has resulted in Neck, Shoulder and back pain. I have been very lucky in the recent past and today that a vehicle was not directly behind me. The seat vibrated first when it sensed the car ahead was breaking. When I started to break, the emergency break kicked in. I did not report this the first time because I thought the car was doing what it was supposed to do. Today was unnecessary. No accident and no police report. I do plan on telling the dealership.

I was backing out of a parking spot when I came in contact with a vehicle going east bound in the parking lot the contact was on the rear right side of my vehicle before I could do anything my vehicle sped up and proceeded to go forward jump a curb I had my foot on the brakes when I realized I wasn’t stopping and heading for a garage I turned right trying to avoid the garage but still hit the corner of garage causing damage then vehicle stopped and shut down.The Vehicle is still being repaired the mechanic said there was damage to a box and cable going to transmission but couldn’t say if it was the fault reported to police end insurance but haven’t gotten any response reported it to General Motors but haven’t gotten a response

Just purchased this vehicle has about 64500 miles on it. When accelerating between 40-55 (hard acceleration) my vehicle wobbles really bad, seems like a tire issue. Have had the front end looked at, and tires all balanced and inspected. Noting out of the ordinary. Then all of a sudden my rear view back up camera works, but my back up assist symbols are not showing/working. I checked the settings and they are turned on. To top off the cake, when the weather is cold outside my windshield wiper fluid will not spray from the front windshield or rear, then when it warms up or is parked in a garage it works again. I have made sure the correct wiper fluid is added as well so it does not freeze. But apparently it is getting stuck somewhere......

Recently I have noticed that the back brakes squeak and sound like they are grinding when backing up. Also every now and then the information screen will go black for a while then turn back on could be a few seconds or several minutes. 23,900 on car

There is a rattle in the b pillar/roof area. They have attempted to fix it 4 or more times by adding adhesive between layers of metal. The fix that other dealerships have done per reading online involves cutting through metal. This would affect the integrity of the body/ frame of the car.

The contact owns 2021 GMC Terrain. The contact stated upon starting the vehicle and attempting to shift the vehicle to drive, the vehicle inadvertently reversed. The contact depressed the brake pedal. There were no warning lights illuminated. The contact stated that the gear shift selector was stuck in park(P) position while the instrument panel was displaying that the vehicle was in neutral. The vehicle was towed to the dealer who informed the contact that they could not replicate the failure; however, the vehicle remained under observation at the dealer. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure but did not provide any assistance. The failure mileage was unknown. The VIN was not available.

While driving my vehicle and talking on the phone, the radio screen went black. Bluetooth or nothing in connection to it was working. After about 2 hours it came back on. I was told to bring to dealership to be checkout, but it came back on. I'm going to take it to the dealership. My vehicle has 13,000 miles on it.

I dropped my son off at school and he mistakenly took my car keys into school with him, and somehow I was able to drive all the way home, 4.5 miles, with no key in the car and no warning to stating the remote wasn't in the car. The issue with this is if I'd driven further, perhaps to another state, or even driven somewhere at night, I would have been stranded once I turned the car off. There was no indication that the remote wasn't in the car, and the car never cut off. I only knew the remote was gone once I arrived home and turned off the ignition. That's when the message displayed that the remote wasn't in the car. I had to call an Uber to go back to my son's school to get the key. This could have been a disaster had I driven further or not had the funds to get back to my son's school. Not to mention if a car thief had someone occupied my car and driven off in it. They could have gotten as far as they wanted (or gas would allow) before the car shut-off as long as they didn't turn off the car. I stopped at stop lights and stop signs and the car just kept going. The issue should be looked into and addressed immediately. This just occurred yesterday. The vehicle has not been inspected and this was the first time anything like that has happened. I normally receive a warning message if my remote isn't in the car even if it's just in the house. This is clearly a defect that needs to be fixed.

My 2021 gmc terrain with 6000 miles on odometer. When driving up hill or going around corner transmission shudders so bad that it feels like front tires are coming off. I contacted the dealer and gm and was told there is a tsb for this complaint. GM and dealer acknowledged there was a problem but they didn't have a fix or known cause of problem

i WAS GOING TO MY SONS HOME WHICH IS LOCATED ON A STEEP DOWHILL STREET WITH SEVERAL TURNS, ONE OF THER ALMOST 90 DEGREES.aS i STARTED TO DESEND THE HILL AND GAIN SPEED, I DEPRESSED THE FOOT BRAKE. iT DID NOT RESPOND AT ALL. AS I CONTINUED TO GAIN SPEED AND COMING UP ON THE SHARP CURVE, I CONTINUED TO PUMP AND APPLY BRAKE . tHE BRAKES DID NOT WORK. i CONTINUED TO GAIN SPEED AND GO AROUND 2 OTHER TURNS. AT THE END OF THE STREET i HAD A CHOICE TO CONTINE STRAIGHT AHEAD AND HIT A HOUSE, TURN RIGHT AND CONTINUE DOWN ANOTHER STEEP STREET UNTIL I HIT A HOME AT THE END OF THE STREET OR TRY TO TURNLEFT ANDGO UP HILL. i TURNE LEFT UP THE HILL AND FINALLY GOT STOPPED BEFOR i COULD PUT THE VEHICLE IN PARK OR APPLY THE BRAKE I BEGAINTO ROLL BACKWARDS ON THE STEEP INCLINE . i ROLLED BY ANDHIT A CURB, JUMPED INTO THE YARD AND HIT A BUSH,SMALL TREE AND AN ELECTRIC GROUND TRANSFORMER, COMING TO RESET ABOUT 4 FEET OF THE GROUND ON TOP OF THE TRNSFORER.. tHE UTILITY WORKERS SAID THAT I WAS LUCKY NOT TO GET EECTROCUTED. tHIS VEHICLE WASPURCHASED ABOUT 7 DAY PRIOR TO THE ACCIDENT, THE BRAKES SIMPLY FAILED ADDID NOT WORK AT ALL

When driving car starting from a red light/getting on freeway or after making turn from a stop light when accelerating between 45 and 60 car shakes when shifting. Problem is getting worse. Car only has 6000 miles on it. I reported it to local gmc dealer and I was told GM is aware of the problem and they do not have a solution. They mentioned there is a TB out for several models that customers have reported same problem