general problems of the 2018 GMC Terrain - part 1

We just got off the bus thruway and my brakes pedal got hard to press and it was hard to stop car I had to push on brake dry hard to get the car to stop it was jarring and o had to get my some and o to a safe place. Garage said it’s brake assist and he researched there’s is an active law suit against gm bc lots of moses and models have this issue although they claim to know nothing about it.

The contact owns a 2018 GMC Terrain denali. The contact stated while the contact's daughter was driving, the brake pedal was depressed, however the vehicle failed to stop as intended. In addition, the contact stated that the brake pedal was unusually hard when depressed. The vehicle was taken to the dealer where the vehicle was purchased. The contact stated that the service brake vacuum pump failed while the vehicle was at the dealer. The vehicle was diagnosed with a failed service brake vacuum pump and a failed engine. The contact was informed that the service brake vacuum pump, the cam shaft and the engine needed to be replaced. The vehicle was repaired. The contact stated that the failure was a known failure of the vehicle. The manufacturer was not made aware of the failure. The failure mileage was approximately 260,000.

Faulty brake vacuum pump!!!! 2018 GMC Terrain @ 119254 miles--- no warning! brakes were hard to press, did not work and I rolled into ditch to prevent an accident. I see hundreds of people with same issue now that I am having to research. This was very scary. I was told it was as a brake booster pressure sensor. But that was not the problem. It is the brake vacuum pump. This is so dangerous. Why is GMC not correcting this issue? this is insane. Gm issued multiple technical service bulletins on vacuum and booster issues starting in 2017. Why hasn't anything been done?.

The contact owns a 2018 GMC Terrain. The contact stated that while driving approximately 30 mph, the brake pedal became extremely difficult to depress, with the message "brake assist" displayed. The vehicle was driven to the shoulder of the roadway and the parking brake was activated, and the vehicle was turned off. The contact stated that the transmission failed to shift into gear, and the vehicle was dragged onto a flatbed truck and towed to the residence. The cause of the failure was not yet determined. The local dealer and manufacturer were notified of the failure, but no assistance was offered. The failure mileage was 132,386.

The contact owns a 2018 GMC Terrain. The contact stated that while driving at an undisclosed speed, the vehicle shuddered and failed to come to a stop while the brake pedal was depressed. The check engine warning light was illuminated. The vehicle was taken to a local independent mechanic, where it was diagnosed with a locked brake vacuum pump. The contact was informed that parts of the brake vacuum pump had entered inside the camshaft and valve cover. Several unknown local dealers were contacted. The vehicle was not diagnosed or repaired because there was no recall associated with the VIN. The manufacturer was made aware of the failure. The failure mileage was approximately 183,000.

The contact owns a 2018 GMC Terrain. The contact stated while driving at an undisclosed speed, the air bag and abs warning lights illuminated. The vehicle was taken to auto zone to be diagnosed. The vehicle was diagnosed with air bag failure. The contact was informed that the air bag needed to be replaced. The vehicle was not repaired. The dealer was made aware of the failure; however, the contact was informed that there were no open recalls on the VIN. In addition, the contact was informed that once a recall repair was completed, it would not be performed a second time free of charge. The manufacturer was not made aware of the failure. The failure mileage was approximately 95,100.

April 2025, vacuum pump went out meaning lost breaks going 60 miles per hour down the road after engine light came on. Left me and two children stranded 2 hours from home with no way to get back except a tow. Now September 2025 cam shafts are out as well as vacuum pump. Stranded boyfriend and I two hours away again. Now metal in oil and warranty is not willing to cover it due to the vacuum pump going out. Made a post on facebook and got lots of feedback on how their newer Terrains have done the same things. Work in insurance and have people car pertaining to their Terrains wondering if we cover engine replacements. There is major issues with these vehicle. Mine only has 107,000 miles on it and I have 12,000 left to pay. The motor is shot and dealership wants to “flush” the metal out of the engine. Very frustrated, I put 12,000 out of my college fund to have a reliable vehicle for my two kids and now this is all I have. A car that doesn’t run. I called warranty and the man I talked to even said that they get a lot of calls for these cars needing to be fixed. I am at a loss on what to do now. The below information about the incident is for the most recent one happening in September. I know that this sounds like a warranty and dealership issue but I guaranty if you send something out to Terrain owners they will report major issues that they have had. Leaving them stuck in loans and no where to go.

Difficulty with power assistive braking when traveling at low speeds.

Component affected: service brakes, hydraulic – brake vacuum pump summary of the problem: I am reporting a serious safety issue involving the brake vacuum pump on my 2018 GMC Terrain. The brake pump failed catastrophically ("blew up"), resulting in a sudden loss of braking power. This occurred without warning and posed a significant risk to my safety and others on the road. We were traveling to vacation in florida and thankfully had just gotten off the interstate. Details: the failure caused the brake pedal to become extremely hard to press, and the vehicle required a much longer distance to stop. We experienced no brake at the brake booster and a blown vacuum pump is due to a faulty vacuum pump which is a known issue for this model. Fortunately, no accident occurred, but the situation could have easily led to a collision. A certified mechanic confirmed that the brake vacuum pump exploded and needs to be replaced. I have incurred significant out-of-pocket repair costs due to this issue. We had to uber to our vacation room, get walmart plus to have groceries delivered to our room. We had to have uber eats deliver other supplies. We have had to walk to various places for dinner and entertainment because avis and budget had no vehicles available to rent and enterprise was closed as we arrived on Saturday afternoon. I have checked for recalls and service bulletins using my VIN, but none are currently listed for this specific issue, despite similar problems being reported in other gm vehicles. Request: I urge the NHTSA to investigate this issue further. The failure of a critical braking component without warning is a serious safety concern. I believe this may be part of a broader pattern of brake system failures in gm vehicles and should be addressed through a recall or safety campaign. Also, the estimate for the repair is $2,500 so any reimbursement would be greatly appreciated. We just received this estimate but I can provide it at a later date.

My car started experiencing a strange problem while braking on June 15. I released the parking brake leaving my parents driveway. I coasted backwards (as usual), and when I pressed the brake the car didn't stop as expected and the brake pedal was very hard to press. It eventually stopped. I put into park, then put the emergency brake on, then released all and tried again and encountered the same issue, that it was very very slow to stop and the brake pedal was hard to push in. I got home, parked the car - tested the reverse brake on flat surface and didn't notice the issue. The next day, the problem started happening with the front brake as well and an error code popped up that said 'check brake assist' which I've never seen before. I brought it to my local mechanic, who took a look and said that it's a vacuum pump failure, and the result is a lot of metal shards were released into the engine when the vacuum pump failed. My mechanic recommended I take to a GMC dealer for further evaluation. I looked up the recall on this issue, and see that it impacts a lot cars, including the 2017 GMC Terrain, but not my 2018 GMC Terrain. I am going to take it to the GMC dealer but I'm afraid I won't be able to afford the repair, and it doesn't seem like there was anything I could have done to prevent this from happening.

Brake booster went out and lost all braking ability on interstate doing 65 mph in spring of 2022 - had brake booster and exhaust cam replaced and April 20 2025 same break and same effect - no braking ability at interstate speed - extremely dangerous situation.

I was slowing down to turn and I couldn't push my brake pedal down it completely locked up. If I wasn't already slowing down I would've hit a power pole and potentially lost my life. My abs light never came on and it's still not on. After I got parked and shut my car off the check engine light came on.

Brake vacuum pump failed causing engine damage. Camshaft on national back order. Vehicle has been in repair shop for 1. 5 months waiting on part. No eta. There has been recall for similar vehicles with same issue, failure, damage. But not for this VIN. It’s the same failure with same damage. How is this not a recall for this VIN?.

I got my car out of the shop a week ago for my brakes the car was in the shop for a month and this past weekend my car is doing the same exact thing a week later I was on I 75 also hit a semi truck.

Faulty brake vacuum pump triggered my brake to get stuck while I was driving ended on the side of the express way to avoid traffic and prevent a crash.

The contact owns a 2018 GMC Terrain. The contact stated while driving at various speeds, the vehicle would not decelerate as intended while depressing the brake pedal. No warning light was illuminated. The vehicle was previously repaired at a local independent mechanic and the vacuum pump was replaced; however, approximately 32 days later the failure reoccurred. The local dealer was not contacted. The manufacturer was not made aware of the failure. The failure mileage was approximately 58,000.

The contact owns a 2018 GMC Terrain. The contact stated while driving 40-45 mph, the vehicle started coasting and stopped unintendedly. The contact stated that the vehicle drove for a while and then coasted and stopped. The message that the “engine power reduced” was displayed. The contact stated that the brake system warning light was also illuminated. The vehicle was towed to an independent mechanic who determined that the camshaft had disintegrated into the engine. The mechanic informed the contact the vehicle was unrepairable. The vehicle was not repaired. The local dealer was not contacted. The manufacturer was not made aware of the issue. The failure mileage was approximately 60,000.

The vacuum pump exploded and I lost power braking ability while going approx. 40mph. If I hadn't pressed down hard on the brakes to slow down, in less than 2 minutes I would have ended up in lake michigan, as I was heading east toward the on ramp for [xxx]. The problem has been confirmed by european us auto here in chicago, and I have photos. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

I have a 2018 Terrain slt. On 11/20/24, I was headed home from my commute to work driving my Terrain with all the confidence in the world because I hadn't had any major issue with it. In 5pm stop and go traffic I decided on another route to my son's school to pick him up from practice. As the light at the end of the bridge turned red, I proceeded to stop, and my brake pedal was as stiff as stone. Going across that bridge I was literally standing up on the brake pedal with my back and shoulder against the roof of the truck for support trying to stop. As I came close to the cars that had already stopped I contemplated jumping out of the car but I decided to keep at it. It was god and god alone that cleared a shoulder for me to be able to pull over. I was petrified!! no signs, no brake noises, no hesitations, nothing! no warning lights on the dash, no alerts, nothing! brakes were just gone! the mechanic said the vacuum pump had exploded and it was a known issue with Terrains and that there was a bulletin regarding this. Pieces of the metal from the exploded vacuum pump were found inside of the engine. The mechanic was upset about the event and said to notify gm, something needed to be done about it. He gave me the vacuum pump to show the gm service center and he said one of the mechanics took pics of the metal in the engine. I called gm and was told to bring it in to a gm service shop so that they could check it out, but at my expense because the manufacturer warranty had expired. I am so upset with gm!! I have anxiety every time I go to press the brake! panic attacks thinking about the possibility of this happening with my kids/elderly parents in tow. Thank god for covering me and all the drivers and their families that could have been hurt. Thank god my son/elderly parents weren't in the car! the fact that this is a known issue and it hasn't been addressed is heartbreaking. Gm should do the right thing and recall these trucks, ASAP.

While driving the vehicle the vacuum pump failed and caused the camshaft to seize and physically break which caused the break peddle to become hard and breaking the vehicle was limited and almost nonexistent, which caused an extremely dangerous situation on the highway.

In 2022 and now in sept of 2024 my entire braking system has failed. Cause you a complete in abilty to stop the vehicle. Upon this failure without any warning peice of the braking system connected to the engine shoots shrapnel into my engine and causes the cam to be destroyed. Now I can't get my car back because of a shortage on this part.

Brake pump keeps going changed in the last 2 week and over in the last 2 yrs 3xs and burning oil. Brakes get hard while driving which is dangerous.

The vacuum pump gears for the brake assist was shattered and metal parts were sent into the engine. I lost power brakes and was lucky to be able to stop the SUV. The car was towed to a GMC dealer where it was diagnosed with a damaged exhaust cam, a shattered vacuum pump and metal pieces in the motor. Cost to fix $3200. This is a 2018 GMC Terrain with 112000 miles on it. I had a powertrane plus warrenty that was still valid but they refused to pay for anything. They claimed the vacuum pump caused the problem and it was not the engines fault. There were no warning check engine lights before this happened.

Vacuum pump is in the shop now being replaced for the 7th time in almost 6 years. The previous one was replaced in September 2023. You get no warning signs, then all of a sudden you can barely press down on the brake petal. This started within the 1st year of purchase.

I was driving down the highway between 65 and 70 mph. The semi-truck in front of me almost missed his turn and stopped quickly to make a 90 degree turn off the highway. I went to slow my vehicle appropriately, and my brakes did not respond. I had no warning that my brakes were compromised. I quickly used the downshift button to use my engine to slow me down and I crashed my vehicle off the road into the sagebrush (luckily no trees and there wasn't a dramatic drop off). At that time, after my vehicle came to a stop, I received a warning on my dash that stated "service brake assist". I looked up the issue on my phone to see what may have happened, and read that GMC had a recall for this very issue. I contacted the dealership and they indicated that they were aware that the 2018 GMC Terrain has this issue, but it was not included in the recall. I am traumatized by this incident. I am a very experienced driver, but I had bought this vehicle for my daughter, had she been driving, this would have been a catastrophic accident. I have nightmares about if this had failed when approaching a crosswalk or in a school zone. If GMC is aware of the problem, and they had a full recall on this on other models with this same problem, why aren't they fixing the Terrain, why are they waiting for a fatality. It is unacceptable, dangerous, and I don't even want to know what the cost is going to be to repair the vehicle. I am thankful it wasn't much worse.

The brakes stop working, they get really stiff and locks in the middle of the highway, very hard to stop and almost caused an accident, it is not the first time, the vehicle was serviced by an authorized mechanic and the problem had been resolved until today, the brakes locked and almost caused me to loose control of the vehicles brake system.

Safety was put at risk when brakes went out without warning, and unable to use emergency brake at that time. Car was serviced for over $1700, with the mechanics stating that the piece “blew up. ”.

While driving on the interstate the brakes all the sudden stopped working. I was able to stop the vehicle by pulling over to the shoulder of the road. I received a warning saying service brake assist and a check engine light after the brakes went out. The vehicle later shut off and is no start with no warning codes. I am currently towing the vehicle to a mechanic. Several people claim to have the same issue online stating that it is an issue with the brake vacuum booster shearing off in the exhaust cam which then causes major damage to the engine. It appears the same issue exists with several other GMC models that were already recalled.

We were driving back from vacation and while on I-95 the brakes went out. The check engine light came on and the service brake assist light came on. My husband was able to pull off to the side of the road but if it weren’t for already starting to slow down due to an accident we were approaching this could have been much worse. When the brakes went out my husband could hardly press the brake peddle. After researching this appears to be a known issue amongst gm vehicles. It appears to be the vacuum pump that went out. There is an open recall for certain models of gm but not all. This was such a dangerous situation. We literally could have died. This should be a recall for all models as Terrains appear to be largely affected as well from this issue.

While driving truck around 55mph with family in vehicle and tried to make a stop in a traffic light, notice truck had a hard brake pedal and did not stop, luckily I (parent) around 50 years of age was able to divert around and put on neutral until truck stoped in side of road. After a while of looking around and checking truck for system errors or lights there was no indication not warnings. I was able to move truck to a near by location and asked a mechanic to go look at it. Mechanic notice oil coming out of brake vacuum pump and took out part and mentioned that the pump had broken in pieces inside engine block and might need a replacement. Truck is still on shop and waiting for our decision to fix. At this point my family is so scared of this truck and don't even want to talk about the incident. Me as a parent is very concern on all this new vehicles that are suppose to be more reliable and better protection than older vehicles , I feel more protected in my 90’s truck. I hope this gets enough attention to at least save someone's life. Thanks in advance, hs.

Vacuum pump failure which leads to total engine repair.

I was driving and my brakes seized up. Could not apply pressure at all. This could have caused serious injury to myself and my daughter as we were driving alone 3 hours from home. I was able to get into a parking lot but now my car won't start.

My vehicle keeps showing “service brake assist” and “service tsc” lights. I was on a hill and the auto-start was engaged, as well as hill assist. When I let off the brake pedal slightly to get the car to come out of auto-start, the car acted like it completely shut off (radio went black and lost power) and the car just started rolling backwards quickly. If there was a vehicle behind me it would’ve %100 caused an accident. My wife and child ride in this car every day and this is the second time I’ve had serious issues with this car. The first time I was driving down the interstate and the brake vaccuum pump went out and I lost all brakes, I had to put all 180lbs of my weight on the brake pedal to get it to stop.

Vehicle brakes went completely hard and vehicle would not stop. There was no warning signs, no lights on the dash and vehicle was driving on highway normally. Upon taking a highway exit, I could not stop the vehicle, completely unexpectedly. Upon further research it is a very common problem that needs to be addressed. My 3 kids and wife were in the vehicle when it happened, and this is actually the second time it has happened. The first time it happened we could not stop the vehicle at all to turn onto the road I live on, could barely push the brake pedal and coast to a stop. The repair last time it happened was the camshaft driven brake booster vacuum pump, and it has failed again after 20,000 miles. This is a serious manufacturer defect that has almost killed my family twice now.

While driving down the road at approximately 55 mph, came up to an intersection, 4 lane I was in the right lane to go straight, there was a right turn lane next to me. I applied the brakes, pedal was really stiff and very slow to respond, I was able to edge over into the turn lane cutting people off and just barely missing the vehicles in front of me. It took 5 car lengths to stop my vehicle. When I finally was able to get the vehicle fully stopped I was almost in the paths of the crossing traffic. . When the light turned green I was able to slowly cross the intersection looking for a safe place to pull over. Immediately crossing the intersection the service brake assist notification appeared, about another half mile the vehicle informed me of loss of power and that it was reducing engine power (limp mode). I was able to find a gas station parking lot to put it. When I opened the hood I noticed quite a bit of engine oil located under where the brake assist pump was located. I had lost about 1. 5 quarts of oil. I refilled that. The next day I returned with a tow dolly. The vehicle was started just long enough to load and unload it at home. We pulled the vacuum pump where upon inspection it was noticed that the part has exploded and so far we are still missing some pieces that may be inside the engine. This is a known and documented problem of this part and should have a safety recall issued. . I still owe over twenty eight thousand on this vehicle and it has only 109,000 miles on it. I hope we can find all the pieces and that the engine wasn't fately harmed. GMC needs to make this right, a lot of people could have been harmed.