On Monday 5/26/2025 I was on the way home from work, coming down my street to turn in my drive (at approximately 2130) I pushed on the brake getting ready to make my turn, my car would not stop. It traveled maybe 100 -200 feet before coming to a stop. The brake pedal would not push in. (As I live on a cul-de-sac, if this happened during the daylight, there would have been children playing in the street and I could have killed someone's child). I managed very slowly to reverse the car and finally get it in the driveway. I thought it was going to hit my house!! Upon reading a lot of issues and complaints on my vehicle make/model I pretty much figured it was the brake vacuum pump. I called GM, however my car has 74,000 miles, is out of warranty and no recalls for my VIN so I'm told I have to have it fixed. My neighbor is a certified mechanic and has a shop. He looked at it and confirmed it is the vac pump. Not only that but the end that goes into the motor has sheared off and not there is metal pieces and fragments in my motor. I had to have it towed to his shop. (this morning) As of right now I am waiting to see if the motor can be flushed or if I am going to end up having to replace motor. I have missed several days of work due to transportation and now have to rent a car, and pay who knows how much for repairs which could easily cost thousands. I live week to week and still make payments on this car!! This is a faulty part and should have been a recall as I have read on many many complaints of bad brake vacuum pump on the GMC Terrains even the 2020 models and up. Some of the others are already recalled but not mine. In the photos, on one you can see the big chunk of metal. On another where the piece came of of motor you can see where metal was scraping the camshaft in the motor and very small metal fragments around the opening
2020 GMC Terrain brakes complaints
Page 3 of 4: complaints 41 to 70 of 73, newest first, as owners wrote them.
The contact owns a 2020 GMC Terrain. The contact stated that the vehicle failed to stop while driving 55 MPH while depressing the brake pedal. The contact pressed the button that immediately shifted the transmission to park, and the vehicle came to a stop. The contact drove the vehicle to a safe parking space. After safely parking the vehicle off-road, the check engine and brake assist warning lights illuminated. The vehicle was towed to the dealer who diagnosed that the brake booster pump and camshaft had fractured and detached from the vehicle. The contact was informed that the brake booster, vacuum pump, and camshaft needed to be replaced. The vehicle was not repaired because the dealer was awaiting the parts to repair the vehicle. The manufacturer was not informed of the failure. The failure mileage was 101,700.
My 2020 GMC Terrain (under 100K miles) was running great until one day, after starting the vehicle, I shifted into reverse and felt soft brakes before the engine suddenly shut off. A licensed mechanic diagnosed the issue, pointing to Technical Service Bulletin #PIP5835, which identifies a defective brake vacuum pump. This failure caused damage to the exhaust camshaft and timing belt, ultimately leading to the recommendation of a full engine replacement. GMC’s response? They advised me to pay for their diagnostics and repairs, then file for a "Goodwill Repair," which they admitted was unlikely to be approved. Meanwhile, GM has since replaced this defective vacuum pump with an electric version, acknowledging the flaw—yet leaving owners like me to cover the cost. I believe GM should stand behind their product and take responsibility for this engineering failure, instead of forcing customers to absorb the expense.
The contact owns a 2020 GMC Terrain. The contact stated that while driving at slow speeds in a parking area and attempting to stop, the brake pedal failed to depress all the way to the floorboard and was firm, requiring an increased effort; however, the vehicle failed to stop as intended. The contact was able to bring the vehicle to a complete stop by turning the vehicle off. No warning lights were illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the brake vacuum pump, observing that the pump had sent metal fragments into the engine, resulting in damages to the engine. The vehicle was not repaired. After investigating the failure, the contact related the failure to Special Coverage Adjustment: N182202780. The manufacturer was notified of the failure, and a case was opened. The failure mileage was 108,000. The VIN was not available.
Brakes stopped working while driving. Yes it has been reproduced by mechanic. No it has not been inspected by manufacturer. “Service Brake Assist” message populated after failure.
my vacuum pump went out. my brakes went out at 86k miles. very pour design.
The contact owns a 2020 GMC Terrain. The contact stated while driving 20 MPH, while attempting to slow down, the brake pedal was depressed; however, the brake pedal felt abnormally stiff. In addition, the vehicle hesitated to come to a complete stop. The contact became aware that the driver's side and passenger’s side struts had failed. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed that the brake vacuum pump needed to be replaced. The brake vacuum pump was replaced, and the vehicle was repaired. The manufacturer was notified of the failure and referred the contact to the dealer for assistance. The approximate failure mileage was 17,361.
In September 2024 i was driving down the freeway and my car shuttered like the transmission was slipping. I then proceeded to get over into the right hand lane incase i needed to pull over thankfully, because then i lost use of my breaks, and then my ability to accelerate and steer. Then my car just shut off and would not stop. My vacuum pump just broke with no warning, it has been replaced and my car still won't start, it's going on 5 months now and they still can't figure out why.
No warning, the brake pedal went stiff as a board. No brakes could not stop doing 35 on a residential road. Had to coast to a stop in neutral.
The brake system failed. No warning. When the brakes failed, driver ran the car into a tree to stop instead of hitting pedestrians or other vehicles
My Terrain has a light that has been coming on for a couple months. Service Brake Assist. I took it to the dealer after my brakes locked up and about $800 after getting it fixed the light continues to come on. The forward collision light comes on every time I start the car. More the check engine light came on and says engine electrical system. What the heck is going on? I love this car and take very good care of it but I feel like the $800 that I just spent was a waste. I fear that I will get in a wreck like when the brakes totally locked up and I couldn't press on them.
Slowed down from coming off of the highway to turn into the gas station and couldn't slow down. The brakes FAILED. Was trying to pump them and was able to come to a forecful stop, nearly colliding with the car in front of me and then again at the gas pump. Car had a failed vacuum pump at 65,000 miles. If this happened during normal rush our, my kids and I would have been sandwiched between two cars. Fatal flaw that clearly GMC already knows about. The Terrain should be included in the recall.
While driving reduce engine power light came on and the brakes gave out. I weigh 250 lbs and took all my strength to get brakes to stop car. I tow it and mechanic showed me vacuum brake pump blew up and went into engine. He replaced that and timing chain but still needed work. Towed it to dealer and it needs a new engine $11 000. The dealer informed me they see this alot. ! Why has GM recalled some on the vehicles that has this pump but not the terrain. This is dangerous. If my daughter was driving she couldn't stop this car. It's now junk.
While driving I had to push the brake to the floor and a light came on saying reduced engine power. I pulled over right away and had my car towed to mechanic. The vacuum brake pump exposed and parts went into the engine. The mechanic got all the parts out but now engine has low compression and needs a new timing chain. This is over $3,000 so far. Gm recalled other vehicles with the exact same pump ? Why not the terrain.
Incident happened August 9, 2020. Brakes suddenly stiffened and unable to stop vehicle. There were no warning signs or indicators. Thank goodness I was going at a lower speed and was able to coast into an area to stop. Ended up being the vacuum pump. This needs to be recalled ASAP. This could have been a fatal accident. I have kept the old vacuum pump as well as the pieces that were thrown from it that the mechanic had to dig out.
As I was driving, brakes became very hard to press. I was barely able to slow down to bring the car to a complete stop. Brakes became very stiff and required a ton of force to come to a complete stop. This came with no warning signs or alerts from vehicle. It was only after this occurred that the Service Break Assist light came on.
The contact owns a 2020 GMC Terrain. The contact stated that while driving 50 MPH, the vehicle lost braking power. The driver was able to pull over safely. There were no warning lights illuminated. The vehicle was towed to the local dealer, where it was diagnosed that the vacuum pump had shattered. The vehicle was repaired, but the failure recurred. The contact reached out to a GMC engineer, who informed the contact that the failure was due to the camshaft reluctor. While driving, the vehicle lost engine power. The vehicle was towed to the same local dealer, where it was diagnosed that the throttle body needed to be replaced. The vehicle was repaired, but the failure recurred. The vehicle was towed to the local dealer, where it was diagnosed that the turbo code had a mass air flow sensor failure. The vehicle was repaired. While driving at an undisclosed speed, the check engine warning light illuminated, and the reduced engine power message was displayed. There was blue smoke detected from the exhaust. The vehicle was towed to an independent mechanic, who informed the contact that the throttle had failed. The vehicle was towed to another local dealer, Power GMC Chevrolet of Newport (1422 N Coast Hwy, Newport, OR 97365) where it was diagnosed that the air pipe charge and air cooler needed to be replaced. The vehicle was repaired. The manufacturer was contacted and referred the contact to the local dealer. The failure mileage was approximately 50,000.
This Saturday morning driving my family to Bradenton as I was coming off the hwy to my exit when I experienced a brake fail I thought, brakes got real hard and I couldn't stop the car on time like I wanted to, so I had to press the brakes pedal harder to come to a complete stop, three different places no one knew what could be the problem until I took it to GMC dealership they can only give a code P0556 / U0401 SERVICE BRAKE ASSIST, seems it was too late to checked out they where about to close , something to do with the busters not sure yet but it's getting checked out tomorrow morning, I was driving on cruise control at a speed limit when this happened, will let you know what's the result of my situation.
Brake booster failed with no warning. Brake pad was hard to push down as I exited the freeway. I came close to hitting the vehicle in front of me which would have resulted in a bad car accident. There were no warning. This is extremely dangerous and is a risk to not only the driver but also to vehicles in the path of a vehicle that cannot stop. This needs to be a recall along with the other vehicles that have a recall for this part.
Heard a ticking noise coming from the engine compartment. I opened the hood to investigate which I first check oil level as sounded like a lifter making the noise but all fluid levels was normal. I drove home and 3 miles later ticking noise went away and my adaptive brake assist came in and the brake pedal was hard to press. Luckily I lived another mile down the road so I got the car home and safely parked it. One of the symptoms is hearing a ticking noise from engine when a braking component fails. Further learned could be a vacuum issue which needs a software update which makes no sense. Had I been traveling highway speeds when this happened this story could have a had a very different tragic ending. Car has less then 53000 miles on it
Driving down the freeway and all of a sudden got a service break assist notification and without warning I was unable to stop the vehicle. I was able to coast my way off the freeway and upon my exit I tried to pull into an empty parking lot but there was a fire fence I ended up crashing into which is probably what brought the vehicle to a complete stop. This is very dangerous and I have read numerous complaints from other 2020 terrain owners who have experienced the same problem. Mechanic stated I need need vacuum pump for brake booster which of course my warranty doesn’t cover. Something seriously needs to be done about this. My accident could have been a lot worse
I was driving on the interstate when my brakes went out. I was able to get off at and exit and pull into a gas station but had to put on the emergency brake.
While on highway service brake system warning light came on,brake became hard to apply almost causing an accident. Vehicle had to be towed to a repair shop(dealer).after paying over $1600 the problem was not resolved and found there are numerous complaints about issues with the terrain and no recall issued.are they waiting til someone dies before a recall?
I was driving down The expressway. The traffic in front of me came to a stop. When I went to apply the brakes I had no breaks. The pedal was as hard as A rock So when I realized I couldn't stop I swerved over into the breakdown lane. And continue to pass cars at a high rate of speed until I got the car to stop. There were no check engine lights on Then I had the car towed to the Dealership Where they tell me is a break vacuum pump. That has damaged The Cam shaft. Pistons and rods in the engine. Totaling $7200. In damage. No one seems to care and I still owe 20000 on the car. Car has 71000 miles on it.
The brake system is only working at about 5%. There are known defects with other GMC models of this year and this vehicle should be reviewed .
Service brake assists light flashes on dashboard . Steering wheel locks up and jerk’s loose suddenly when making a right turn, in these moments when the steering wheel jerks loose ;hands are off taken off the steering wheel otherwise injury can occur. Battery life 2 -yrs old is not performing optimally. Can not hold a sufficient charge and ESC light flashes. Vdnt valve leaks discovered.
My service brake assist light came on and then within seconds my vehicle then said engine power has been lowered and my vehicle pretty much shut down no steering no brakes couldn't do anything. Took it into the repair shop and my vacuum pump has shattered and now damaged my camshaft. I am aware there's been many other vehicles recalled with GM's vacuum pumps and I'm not sure why my year and model has not been included when it's doing the same thing and not to mention I have seen countless other cases of people saying same things happen to them with their GMC terrains.
Unknown...acts as if its a smart car that's not really a smart car
Brakes hard to press. Almost cause an accident on interstate. Was able to contain vehicle. Took to autozone to assessed and it said Powertrain System. Brake Booster Senor Circuit.
The contact owns a 2020 GMC Terrain. The contact stated while driving at various speeds, the vehicle lost brake functionality while depressing the brake pedal. The contact stated no warning light was illuminated. The vehicle was towed to a local dealer where it was diagnosed with needing the vacuum pump replaced. The vehicle was repaired however, the failure persisted. The manufacturer was not informed of the failure. The failure mileage was approximately 40,000. The VIN was unavailable.
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