Service Brakes Problems of GMC Terrain - part 2

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.

See all problems of the 2018 GMC Terrain 🔎.

Failure of the cam driven vacuum pump causing brake failure. Leading to a hard brake pedal which increases risk of a crash. Debris from the broken vacuum pump can fall down into the engine causing a catastrophic failure of the engine needing a replacement. This happens with little to no warning. Warranty companies will not pay to repair the known issue. A recall needs to be issued for this to provide a fix. This is a family SUV and I do not feel safe putting my children in a vehicle that can endanger their lives and safety.

See all problems of the 2019 GMC Terrain 🔎.

The system that failed was the brakes, the car is availble for inspection. My saftey and others was put at risk due to not having brakes to stop. The problem has been confirmed by a dealer as a master brake cylinder failer the vehicle has been inspected by the dealer. There were warning lamps, message and other symptoms of the problem prior to the failure. They first appearead on December 4 2025.

While driving my brakes failed. I was unable to stop my car, my brake pedal became very stiff and I could not stop my car. There were no warning signs or lights on indicating there were any issues with my car prior to this happening. I had to have my car towed to the dealer. The current estimate is for a vacuum pump failure resulting in camshaft damage. Both need to be replaced. I see other GMC cars were recalled for what appears to be a similar issue. I am lucky no one was injured as this could have very easily resulted in a fatal event. I have never heard of such a thing happening before and am beyond belief that this has occurred. This is the third repair I've had done this year. I have also replaced a booter pipe and valve gasket due to leaking oil. The amount of repairs required in such a short a time seems excessive.

See all problems of the 2020 GMC Terrain 🔎.

While driving on a main road at around 45mph the vacuum pump that supplies brake fluid to the brakes failed. The car was unable to be stopped and had it not been late in the night I could have crashed into other vehicles on the road or hit someone walking. There was not indication prior to the malfunction and was very sudden. This issue has been observed by the dealer as well as multiple other individuals with the same problem for this make and model of car as well as others by the same manufacturer for similar years of manufacturing. This part has also been shown to break into the engine causing complete engine failure due to lack of a shear pin on the vacuum pump.

My cars breaks failed by a vacuum pump failer and I almost died on the a hill going home.

The contact owns a 2020 GMC Terrain. The contact stated that while driving up the driveway at approximately 10 mph, the brake pedal was depressed but failed to function as intended. The contact used force to depress the brake pedal. When the vehicle came to a stop, there was an abnormal grinding sound coming from the front brakes. The contact stated that the message "power assist brakes" was displayed on the instrument panel. The vehicle was not taken to the dealer or an independent mechanic. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 198,000.

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.

Vacuum pump went out. It was a recall, previously on older models, but this model needs to.

I filed a complaint with NHTSA on November 3, 2025, about my brake system. Here is another one adding more information. I had to have another brake system part replaced. This time it was the brake booster. Cost $1441. 63 (covered by extended warranty actual cost to me $100. 00. ) so far, I have had the booster sensor replaced twice, the vacuum pump and now the brake booster. I asked the mechanic how many parts related to this system were left to replace? this vehicle has 66,000 miles on parts for the braking system started needed to be replaced at 37,000 miles. The total cost for parts, labor is about $500. That does not include the loss of use for this vehicle which is about 15 days. Taking days off of work about 6 days. This has been a problem for GMC Terrains since 2015; there is still a problem with 2020 model year. Please do something before there is a loss of life due to brake failure.

Check engine light is on took vehicle to dealership 10/13/2023 vacuum booster sensor replaced (37,435 miles) $0 gm covered cost 12/9/2024 brake vacuum pump replaced (56,456 miles) $0 extended warranty 1/8/2025 vacuum booster sensor replaced (57,087 miles) $252. 48 not covered by warranty check engine light is on 10/11/2025 took to dealership. They were unable to find issue light was off, was told that gm had recommended several things that could be the cause of light coming on still could not find issue. Last thing gm and dealership recommended was to replace the battery. Cost $104. 00 check engine light came on 10/25/2025 while returning home from tennessee to michigan, light came on in louisville, ky. Had it scanned, booster sensor was the cause. Called aaa had them replace battery light went off. (as you know that if you do that it reset the computer not surprised light went off drove rest of the way home to michigan) cost of replacement battery $295. 00 check engine light came on again 11/2/2025 my best bet is that it is booster sensor again. Nhtsa and gm need to fix this issue. I have not lost breaking ability yet but the horror story that I've read on this site scars me. What are is NHTSA and gm going to do wait until someone is killed because of this issue !!!!!!!!.

Break assist light comes on and brakes stiffen suddenly with no warning. Happened 6 times now in a 3 year span. Gotten it "fixed" each time but it keeps happening.

When approaching a stop sign, the brake pedal became extremely hard I was unable to stop, and rolled through the intersection avoiding collision. I was able to slow down enough to engage the emergency brake. There are no lights on the dash.

Driving approximately 70mph on interstate. Came to a slight hill, gently applied brake pressure, brakes become hard to apply/would not apply. After diagnostics, found brake vacuum pump with damaged fins.

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.

On my 2020 GMC Terrain the vacuum pump failed and caused my braking system to go out completely. I had to almost stand up on the brakes to get the car to stop and thankfully I got it come to a stop before smashing into another car. I contacted GMC and while they know this is a ongoing problem and there is a warranty out for this particular problem (150,000 miles or 10 year warranty) I was told it is part/ factory specific and that if it was manufactured in certain facilities or had certain parts that they would cover the cost to fix it but however my vehicle was not covered. This poses a dangerous problem for GMC owners. As soon as the check engine light came on I had absolutely no control over the brakes and it was a miracle it stopped. There was no warning prior to this incident and upon looking up information this seems to be a recurrent problem that GMC needs to address seeing as they say they value their customers.

My 2020 GMC Terrain brakes pump failed causing me to hit the median wall on the highway.

While driving my 2020 GMC Terrain (VIN: [xxx] ) with approximately 110,501 miles, I experienced a sudden and complete loss of brake assist. After about 2 hours of highway driving, I exited and the brake pedal became extremely hard to press, making it very difficult to stop. No warning lights or messages appeared before the failure. The dealer diagnosed the cause as the brake booster vacuum pipe exploding internally, which immediately eliminated vacuum to the booster. This created a serious safety hazard and nearly caused a crash. I have since had the part replaced, but the fact that this component can fail without warning at highway speed is alarming. Gm has issued TSB 21-na-107 describing this exact failure mode, which indicates it is a known issue. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

I was backing out of the driveway, and it was extremely hard to brake enough to stop the car. I immediately parked back into the driveway. I had to stand on the brake to completely stop. Vacuum pump was completely busted and in many pieces.

Driving down the road and an engine power reduced light came on and then the driver was not able to apply the breaks to stop the car. Almost ran into a car at a 4 way stop before getting the car to stop.

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.

I was driving my morning commute to work, when I came upon a stop light. I was pressing the brakes and the brakes failed to engage which caused me to hit a car in front of me. I did not have any warnings that the brakes were defective. The warning on the dash did not indicate that there was anything wrong with brakes. I had my set belt, was going the speed limit and my brakes just gave out. I have injury’s to my arms, shoulder, neck, and head. The other vehicle driver was not hurt. Thank the lord.

See all problems of the 2016 GMC Terrain 🔎.

Two weeks ago I was driving on the highway. My car felt fine. No warning light the dashboard. Suddenly I receive a notification on my dash stating “engine speed reduced” and my check engine light went on. My car at this point still feels fine, not shaking, no smoke, etc. I’m on the highway and not in a safe position to pull over. 2 minutes later I receive another notification on my dash stating “service breaks”. I immediately tap my brakes to check and they are stiff. I let off the gas as I was approaching the exit and begin pumping my brakes. They continue to be stiff. Luckily there was no one I front of me as this exit led to a rotary. I was able to coast around the rotary and into a parking lot where I attempted to push the e- break which did not work. My steering tightened and then my car died. I have the car towed to GMC where I bought the vehicle. Am told I will be charged a diagnostic fee and they will let me know what they find before repairs are made. I receive a call back the following day stating “the vacuum pump exploded causing you to loose brakes”. I was told “the vacuum pump and repairs would be about $1,200. But they could not guarantee that once the vacuum pump was removed, there wouldn’t be more debris and destruction to the cam shaft and engine”. We asked they continue with the diagnostics and check the engine for debris. We receive a call back stating “the vacuum pump exploded and there are shards of medal debris in your engine”. Recommendations are that I need a new engine as "the vacuum pump explosion caused catastrophic damage to the engine". My safety and the safety of other innocent drivers on the highway were put in extreme danger! I lost all break control, power steering, and emergency break control. I had minutes from the time the first warning alerted to the time I lost complete control of the car. This is a known issue with gm motors specifically made between 2016-2019.

While driving the vehicle the car went into limp mode and the back brakes stopped working. The car had to be drifted into a parking lot. The vacuum pump malfunctioned and has damaged the engine. If it was me in the driver seat instead of my partner, the incident would’ve 100% been an accident. The car was really unable to be controlled and we just happened to have that space that was empty to turn into. The car gave code when this happened. When getting a tow the car also wouldn’t take itself out of park or start to go into neutral to move the car to get it towed. Nothing is working with each other anymore and we were on a busy road of people when our brakes just went out.

Driving down busy highway and suddenly had no brakes!!! no lights came on dashboard as a warning. Found out it was a braking pump that broke and shot metal pieces into the engine. Now im facing a new engine for a 2020 Terrain!!.

I was driving on the expressway, attempted to brake and the brakes were stiff and would not go down to stop the vehicle. . Thankfully, I was able to glide over three lanes of traffic and exit the expressway and glide into a parking lot and drove around until the car came to a stop. No lights. No warning. The car had to be towed to my mechanic. This could have been catastrophic. I could have killed someone else or myself. This is the second time that this has happened with this vehicle!!! by the grace of god I am still here writing this complaint. I am traumatized and do not feel safe driving this car. They must recall this vehicle before somebody gets killed. The issue is with the vacuum pump and I have seen other complaints about the same issue.

Master cylinder , less then 1000 miles was pulling out of a parking lot and the brakes went out.

As I was driving down the ohio turnpike on my way to work on Tuesday, August 5, 2025, my check engine light came on. Almost immediately I got a notification that the car was operating at reduced power. I had no previous issues with the vehicle. As I got off the turnpike my braking system failed. I was able to come to a stop partially in the grass before entering into oncoming traffic. The entire car shut down. I was unable to restart the car. We were also unable to put the car into neutral to push it off of the road the remainder of the way because the wheels were completely locked up at this point. The parking brake was engaged on its own. We also could not get the car into neutral. I had the car towed to a local repair shop, not knowing at all what the issue was. The vacuum pump had failed and broke apart in the engine. This caused my braking system to fail completely also. The vacuum pump on my 2020 GMC Terrain has been noted as faulty or defective. However, an official recall has not been issued for my vehicle. Had the pump failed a moment sooner I could have been in a crash trying to exit the turnpike. I took my vehicle to a repair shop and spent $1400 out-of-pocket. The car still does not run correctly now as there are pieces in the engine of my vehicle that were unable to be retrieved.

Friday July 25, 2025 I was driving my 2019 GMC Terrain sle and when exiting the interstate the brake pedal got hard and I could not stop. After almost rear ending another vehicle, I got the vehicle into the ditch and safely off the road. After several attempts to correct the problem, I was unsuccessful. The vehicle was towed home and seen by a mechanic. The vacuum pump went out while I was driving.

While working out of town for work my engine light started flashing and the dash lights went nuts. My brakes were nonexistent and were hard as a rock. I had zero warning as to what happened. Working 3 hours away from home the car had to be towed and I was informed the engine code came back as my cam shaft. Took it to the dealer as gm has a bulletin put out. I didn’t know what that meant. Long story short and 3000. 00 dollars later I find out that the vacuum pump exploded which cause the cam shaft to fail. I was out of work for almost a month. There is a recall for almost all vehicles from this year but not the 2019 Terrain even though it contains the same vacuum pump as all the recalled makes and models. Vacuum pump, cam shaft, oil pan, oil pump had to all be replaced at under 100,000 highway miles. Someone needs to address this problem.

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.

I was driving on the highway & my brakes failed. My brake pedal was completely hard & could not be used. I had to steer onto an exit ramp & be towed to the dealership. There was absolutely no warning of this happening. Once at the dealership, they confirmed it was my vacuum pump that blew up, which damaged the camshaft & caused pieces of metal to be floating around in my engine. The greater portion of the repair was covered under warranty, however, I had to pay $350 out of pocket. This could have been catastrophic. I or others on the road could have been injure for worse. This system failure should be fixed immediately and owners be compensated. I do not feel safe driving myself or my family in this vehicle after experiencing this occurrence.

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.

See all problems of the 2021 GMC Terrain 🔎.

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.