2018 GMC Terrain Brakes

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?

Difficulty with power assistive braking when traveling at low speeds

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.

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.

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 pedal. This started within the 1st year of purchase.

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.

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 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.

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.

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 [XXX] 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, [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

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.

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)

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.

Driving on highway and all of a sudden I could not break - the car breaks failed to operate - had to slowdown by it self and pull to a McDonalds, I had the loss of effective braking with no warning whatsoever. We found out that the Break Booster Pump was destroyed without any warning from the electronics of the SUV.

The contact owns a 2018 GMC Terrain. The contact stated while driving 45 MPH, the check engine warning light illuminated. The contact stated while making a left turn the brake pedal was depressed but failed to stop the vehicle. The contact was able to continue driving without proper braking response to her residence. The contact stated she used the parking brake to fully stop the vehicle. The contact's husband took the vehicle to the local dealer, where it was diagnosed with needing an unknown pipe and vacuum pump to be replaced. The vehicle was not repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 79,000.

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.

Brakes go to floor an brake peddle starts to vibrate, (lost of brakes ) Brake assist light comes on. Vehicle has 27000 miles . Problem started at 6000 miles an was brought to GMC service centers 3 times for same issue. They replaced 3 different parts at a total cost of1600 dollars. Brake system is being replaced one part at a time at my expense, GMC has no clue what problem is. Will not admit there is an issue? Just got vehicle back for 3rd time an 3rd new part .

The brakes are extremely hard to engage while driving. All 4 rotors are pitted with less than 30k miles. Doing some online research this is a common problem and should be addressed. I just did my first set of brakes at 100,000 miles on my truck.

Brake has to be pushed all the way down HARD to stop, brake assist warning comes up. I’ve had the car for less than 2 years and it’s way too new for anything to go out. Undriveable unless it’s fixed.

When trying to brake, brake pedal became extremely hard to push and Repair brake assist notification and check engine light came on

I was driving out of town (2 hrs from home) with my 2 small children and my mother, when I tried to slow to come to a stop my breaks did not work and I almost rear ended someone. It was sudden, there were no signs that my breaks were going to mess up. When I tried to look up recalls, there were none for my vehicle BUT there were MANY statements of people who drove gmc or gm vehicles that had the same issue with the vacuum boost for the brakes around 50k miles where the breaks just quit or were hard to use. It seems to be a common issue and is VERY unsafe. I cannot afford to fix the issue and I don't feel as though I should have to if other terrains have been recalled, except mine which I do not understand.