Service Brakes Problems of GMC Terrain - part 1

VIN: [xxx] mileage: approximately 103,576 incident location: [xxx] safety complaint: while my wife was driving our 2019 GMC Terrain into a shopping center parking lot, the vehicle suddenly experienced a severe loss of braking assistance. The brake pedal became extremely stiff and difficult to depress, and she was barely able to slow the vehicle. This occurred unexpectedly while the engine continued running, creating a serious risk of a collision. Following the incident, I inspected the vehicle using an obd-ii diagnostic scanner, which identified diagnostic trouble code p0016 (crankshaft/camshaft position correlation). The vehicle also displayed an oil-pressure warning. We subsequently had the vehicle inspected by john's automotive care in [xxx] on xxx. During the inspection, the technician discovered a significant amount of metallic debris in the engine oil. The repair facility suspects a mechanical failure of the engine-driven brake vacuum pump, potentially resulting in damage to the engine and lubrication system. The repair facility recommended replacing the mechanical vacuum pump and engine oil-pressure switch and performing an oil change. However, the service representative explained that these repairs would not guarantee the engine's continued reliability because the engine was compromised and could fail at any time. We are extremely concerned that a failure involving the brake vacuum pump could cause sudden loss of braking assistance without adequate warning, potentially resulting in a serious accident. We request that NHTSA investigate whether this failure represents a safety-related defect affecting the 2019 GMC Terrain and other vehicles equipped with similar engine-driven brake vacuum pump systems. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

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Without any type of warning, I was driving down the road when my car started making a knocking/ticking type noise then my engine light came on. I attempted to hit my brakes and stop, and I had no control. There was no brakes without pushing it all the way to the floor it was very hard to get my car to stop. I managed to get off the road and into a parking lot and now told that I have $5000 worth of repairs, including the vacuum pump, camshaft timing and guides. After reading information I see there is complaints filed regarding this failed vacuum pump and I would just like to report this.

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On September 25, 2026, while driving my 2018 GMC Terrain sle 1. 5l turbo on the highway at approximately 70 mph near anderson, indiana. I experienced a sudden loss of power brake assist without any prior dashboard warning lights or messages. I was traveling with children to sandusky, ohio for a youth wrestling tournament, approximately 5 hours from my residence. The brake pedal became extremely hard to press, requiring excessive force to slow the vehicle while traveling at highway speeds. I was transporting children at the time, creating a serious safety concern. Because I was away from home and needed to get the children to their scheduled wrestling weigh-ins, I arranged alternative transportation through enterprise. I was unable to have my vehicle inspected by a GMC dealership until September 29, 2026, after returning home. At approximately 93,614 miles, ed martin Buick GMC diagnosed an internally failed, engine-driven brake vacuum pump. The service advisor confirmed in writing that the pump had come apart internally and explained that a seized pump can strip the exhaust camshaft gear. The dealership documented missing metal material from the vacuum pump and camshaft gear, raising concerns about metal debris entering the engine. Diagnostic trouble codes included p0014, p0017, and p0556. The dealership estimated repairs at $5,960. 79 but advised that the proposed repairs might not remove all internal metal debris. The service advisor stated that replacing the engine would be the only way to guarantee complete debris removal. Gm has published technical service information, including pip5835 and bulletin 21-na-268, addressing similar vacuum pump failures and associated damage. The vehicle remains unrepaired. I am reporting this incident because an unexpected loss of power brake assist at highway speeds, without advance warning, creates a significant collision risk for drivers, passengers, and other motorists.

While driving on an interstate, vehicle became sluggish when accelerating. Took off on exit, engine was reduced to 50% power, attempted to drive to large parking lot, lost brakes, got the vehicle stopped in an intersection, would not shut off, go into neutral. Finally shut off, had to call tow truck, holding up traffic in a busy intersection. Was told it would be just $900 to fully diagnose problem, but it appeared the vacuum pump failed, threw broken metal into engine and now will have to be replaced at my cost. No advanced warning of any type of problem, no warning lights, etc.

While driving at the speed limit the vacuum pump failed on my 2020 GMC Terrain. This failure led to me enter an intersection with heavy cross traffic, nearly striking g several vehicles. This is the 3rd time I have had to replace this pump in 2 years. The pump explodes sending chards of metal into the engine leading to more damage and labor intensive work.

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On 9/15/2026, my wife drove her car, a 2019 GMC Terrain, to a doctor's appointment. She reported no known issues with the way the car operated during her drive nor had she or I experienced issues prior to this event. After she finished her appointment, she attempted to start her car and was unable to get the car to start. She also noticed that the brake pedal was stiff and hard to depress. When I arrived, I tried to assist her, thinking that an electrical issue was the fault. However, I was still unable to start the car and I had to have it towed after I couldn't start her car. I had it towed to a mechanic who initially thought the car had a bad starter, however, after attempting to manually turn the engine, he found that the engine was completely seized. He also confirmed that the oil in the car appeared to be without fragments in it and that the oil level was adequate for normal operation. This car is only seven years old, has had routine maintenance, and is about 60 miles over 100,000. No prior issues were noticed before this happened. I'm currently waiting on an engine for the car so we can start using it again.

The contact owns a 2018 GMC Terrain. The contact stated that while driving 20 mph, the brake pedal was firm and the "service brake assist" message was displayed on the instrument panel. The contact used excessive force to depress the brake pedal while stopping the vehicle. The vehicle was driven to the destination and parked. The dealer was notified of the failure and informed the contact that the vehicle was not included in a vacuum pump recall. The vehicle was not diagnosed or repaired. The vehicle was scheduled for repair with an independent mechanic. The failure mileage was approximately 116,000.

While driving my 2020 GMC Terrain, I experienced a sudden loss of normal braking assistance. I had been traveling on the highway and exited onto a main road. As I approached a red traffic light at approximately 50 mph and attempted to brake, the vehicle would not stop normally. I was unable to stop for the red light and went through the intersection before I was able to safely get the vehicle off the roadway. Fortunately, there was no vehicle directly in front of me and I was able to make it through the intersection before any other cars, so no collision occurred. The vehicle was subsequently inspected and diagnosed by a GMC dealership. A diagnostic scan performed after the incident showed code p0556 for the brake booster pressure sensor circuit range/performance. The GMC dealership later diagnosed problems involving the vacuum pump, exhaust camshaft, and timing components and recommended replacement of the vacuum pump, exhaust camshaft, timing components, and related parts. ” the sudden loss of braking assistance created a serious safety hazard and could have resulted in a collision, serious injury, or death. The vehicle is currently available for inspection.

While driving my 2019 GMC Terrain with three children as passengers, the vehicle developed a braking/engine problem. The brake pedal became very hard, and the vehicle subsequently became undrivable and would not start. I received no advance warning through the GMC app indicating that the vacuum pump was failing. The vehicle was towed to a GMC dealership. The dealership diagnosed a failed vacuum pump and advised that the engine requires replacement, with an estimate of approximately $11,238. I purchased this vehicle new. I am very concerned that a vacuum-pump failure can result in reduced brake assist/increased brake-pedal effort and major engine damage without adequate advance warning. Three children were in the vehicle when this occurred, and the sudden change in braking created a serious safety concern for everyone in the vehicle. The vehicle is currently at the GMC dealership. I have requested that relevant parts be preserved and am requesting gm policy assistance with the repair.

The contact owns a 2020 GMC Terrain. The contact stated that while driving at an undisclosed speed, the vehicle failed to stop as intended. The brake pedal was depressed to the floor, and the vehicle slowed down and eventually stopped. The vehicle was taken to an independent mechanic, where it was diagnosed with a failed vacuum pump. The mechanic informed the contact that the vacuum pump needed to be replaced. The vehicle was repaired. The contact stated that the failure was a known issue with the vehicle. The manufacturer was not notified of the failure. The failure mileage was approximately 92,000.

The brake suddenly became impossible to depress more than 3/4 of an inch. Almost unable to stop nearly hitting another vehicle. The dashboard then lit up with a "service brake system" warning. Luckily was only a few minutes from home brought it home and began the search for the issue. The brake vacuum pump failed. Unsure of further damage at this point. It being Sunday am unable to contact a shop or dealer.

While driving, I suddenly smelled something burning. Immediately after, a warning popped up stating 'engine power is reducing,' the check engine light came on, and I experienced a sudden, near-total loss of power braking assist, making the brake pedal extremely hard to press. I had to use intense force to bring the vehicle to a stop. A scan of the vehicle's obd-ii codes revealed codes p0556 (brake booster pressure sensor circuit), p0014 (exhaust camshaft position timing over-advanced), and p0017 (crankshaft position - camshaft position correlation). This is a known failure where the engine-driven mechanical brake vacuum pump seizes up, destroys the braking vacuum assist, and bends or shifts the exhaust camshaft reluctor wheel, causing a severe and immediate safety hazard while in motion.

Approximately 3 miles from my residence my car display flashed "reduced engine power" and slowed down. When I reached a stop sign and tried to stop, my brakes were stiff and I was unable to stop. I went through the stop sign. I continued to my residence at 10mph and backed into a parking space with a curb to help stop my vehicle. I turned the car off and called a mechanic to come look at my car. I explained the events and let him know it would not start. He checked the codes after hooking it up. The error codes were for cam shaft and crank shaft, etc. I was instructed to not try and start the car because further damage could occur and it would need the camshaft pulled to determine the extent of damage.

The contact owns a 2018 GMC Terrain. The contact stated that while her son was driving 45 mph, the brake pedal was firm while depressed. There was no warning light illuminated. Due to the failure, excessive force was needed on the brake pedal to stop the vehicle. The contact was able to drive the vehicle to the residence. The following day, the vehicle was taken to an independent mechanic. The mechanic diagnosed the vehicle with an inoperable vacuum pump that was shredded and needed to be replaced. The manufacturer was notified of the failure and informed the contact that the VIN was not under recall. The contact was then referred to the NHTSA hotline for assistance. The vehicle was not yet repaired. The failure mileage was approximately 117,000.

On Saturday, August 15th we were driving on the freeway when with no warning the check engine light came on and the vehicle began to run poorly, and then the vehicle lost electrical power and it became difficult to steer and the brake pedal became stiff, making it difficult to stop and pull over. The vehicle would not start on command but kept running very poorly, it also became impossible to shut the vehicle off until it seized. It was later towed to a local repair shop, and today, Friday August 21st the shop confirmed that the vacuum pump on the brake assist failed and it would need a total engine replacement.

While driving my 2019 GMC Terrain on local roads, the vehicle suffered a sudden and complete failure of the braking system. The brake pedal became extremely hard to press, and the dashboard displayed a critical error message stating 'engine power is reduced. ' during this frightening safety incident I felt lucky to bring the car to a stop without an accident. The vehicle had to be flatbed towed to a repair facility. This sudden loss of power braking is a known, documented defect matching the engine-driven brake vacuum pump failures currently subject to federal class-action litigation (thieme v. General motors). I am requesting a formal safety investigation into why the GMC Terrain was excluded from previous gm vacuum pump recalls despite posing an identical, life-threatening risk to occupants. ".

The contact owns a 2018 GMC Terrain. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed; however, the vehicle failed to stop as intended. The contact stated that the brake pedal was abnormally firm. The brake pedal was depressed to the floor, and the vehicle came to a stop. The check engine warning light was illuminated. The vehicle was towed to the dealer. The vehicle was not diagnosed. The contact referenced an unknown recall; however, the VIN was not associated with a recall related to the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 95,300.

While driving my 2018 GMC Terrain, the vehicle suddenly displayed an “engine power reduced” warning and the brakes became extremely hard to press. The vehicle experienced a sudden loss of normal power-brake assist while it was in motion, creating a serious safety risk because significantly greater pedal force was required to stop the vehicle. I was able to pull over safely. After stopping, the vehicle would crank but would not start. The vehicle was towed to a GMC dealership for inspection. The dealership documented that the vehicle had a suspected failed/broken vacuum pump, a damaged exhaust camshaft, and a damaged exhaust camshaft actuator. The dealership subsequently documented that the engine was severely sludged and stated that the sludge caused the vacuum pump to fail, which then caused the exhaust camshaft to twist and damage the exhaust camshaft actuator. The dealership’s written diagnosis recommends replacement of the exhaust camshaft, exhaust camshaft actuator, vacuum pump, and associated one-time-use parts. The dealership has also documented diagnostic trouble codes p0014 and p0017. The failed vacuum pump and related components should be available for inspection upon request. The vehicle has been inspected by a GMC dealership, which has documented the suspected vacuum pump failure and resulting engine damage. The sudden loss of power-brake assist occurred while the vehicle was being driven and created a potentially dangerous loss of braking capability. I am reporting this because I believe the failure of the vacuum pump and resulting loss of brake assist may represent a safety-related defect requiring investigation, particularly because the vehicle experienced a hard brake pedal without prior warning.

Vehicle would slowly roll even when break is applied. It was confirmed by the service center that the break booster vacuum pump was only reading 8 when it should be at 27. It was not making enough pressure. The vehicle would not stop when break was applied.

While driving north in interstate 79, the brakes became very hard to push making it difficult to stop the vehicle. We got off the interstate and proceeded back home. The brakes were as hard as a rock to push and it was difficult to stop the vehicle. When this happened, the check engine light came on and stayed on. It was very dangerous to drive due to the brakes not working properly and the stopping distance was greatly reduced and it was difficult to stop the vehicle putting our family at risk for their safety. We took the vehicle to a repair shop and they checked and diagnosed the issue and told us the vacuum pump for the brakes was no good and needed replaced. We found that this is a common issue for breakdown on our type of vehicle. Repairs were made and the total cost was $352. 24 including tax.

I was traveling down the interstate at 70mph. Traffic began slowing ahead of me. I hit the brakes and the pedal was rock hard and I could not stop my vehicle safely. Service brake assist light flashed momentarily. Ended up being the vacuum pump. I was told by the dealership I had it towed to that the vacuum pump had broken off and failed. This was an absolutely horrifying situation that could have caused severe injury or death.

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

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The vehicle has had regular maintenance, oil change, and inspection including the brakes. My boyfriend is visiting me in [xxx] from the [xxx]. Onxxx while driving the vehicle the engine started. Making a ticking noise especially during idle and when accelerating in idle. About 15 minutes after the ticking stopped and all of a sudden there's a complete loss of breaks they locked up and the driver was unable to efficiently stop while going down a hill road. Driver had to use the emergency brake to make the other brakes release and then the brakes from there would not work even though you could stomp on them stand on top of them there was no breaking power anymore. Vehicle was brought into a GMC dealership on the following Monday where they confirmed the issue was a failed vacuum pump connected to the engine and camshaft which is a known safety issue to GMC as part of an ongoing open case they had specialty coverage and bulletins regarding the tahoe and sierra but neglected to include the Terrain on this issue. Cold the GMC manufacturer in both [xxx] and [xxx] to try and get cost assistance and specialty coverage as the vehicle as well under the mileage requirements but have been giving the push around and zero assistance. The risk to the drivers and passengers lives was significant as we were on the highway for1. 5 hrand thankfully the brake lost didn't happen in full during that time. The repairs were completed and paid for in full by the client which should have been covered by the dealership and we are looking for cost recuperation and are now being ignored. Receipts are here to substantiate the claim. The abs light is no longer on there was no warnings on the vehicle showing any issues or any codes as onstar was called and diagnostics were received and the diagnostics came back clear prior to this happening, and following the break failure. Lack of codes and warnings is life-threatening and serious. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

My vehicle is making a squeaky sound/noise when breaking and getting louder. I took it in for service and they couldn’t seem to find the issue. It’s coming from the front end of the vehicle.

The contact owns a 2015 GMC Terrain. The contact stated that while driving 5 mph, the brake, abs, and stabili-trak warning lights were illuminated. The dealer was contacted and diagnosed the vehicle with an electronic brake control module failure. The dealer stated that the manufacturer no longer manufactured parts to repair the vehicle. The manufacturer was not made aware of the issue. The failure mileage was approximately 167,446.

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Vacuum pump failure causing sudden and unexpected hard brake pedal and loss of braking coming off the highway. Ended up catastrophic engine failure. This is the second incident with this vehicle of the exact same problem. GMC refuses to address this issue and continues to risk the lives of their customers.

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 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.

Abv came on. Scr alerted I needed service. On a 25 mph road I no longer could brake randomly.

On June 7, 2026, I was driving my 2020 GMC Terrain. I was going at about 40mph along a very busy main road. While slowing for a red light the check engine light turned on and the car displayed a notice about reduced engine power. Seconds later, the brake pedal became stuck and would not press down all the way and I lost braking ability. The car rattled/shook violently, made a grinding noise, and then the engine shut off and the car stopped abruptly, narrowly avoiding hitting the car in front of us. I turned on the hazard lights. I was not able to get the car to start again, nor was I able to get the car to shift into any other gear including neutral. We were nearly hit by other vehicles multiple times while attempting to get the car to move again, and to get myself and my child safely out of the road. Myself and multiple bystanders attempted to engage the transmission interlock override multiple time. We were eventually able to engage it and push the car to the side of the road. This failure created an extremely unsafe situation for all involved as this road is very busy and there were numerous near-collisions both with my disabled vehicle, and with other drivers serving out of the way and into other lanes at the last second. As time went on and the battery drained, most of the car's exterior lights turned off and other drivers had a hard time seeing my car. I used a strobe flashlight to alert other drivers but this required that I had to stand in the road near the vehicle. Police were called immediately when I found that we could not move the car out of the road, but they did not arrive. Ultimately the vehicle was stuck and inoperable in a travel lane for over two hours. The car was then towed to a nearby repair shop. The mechanic evaluation stated that the brake vacuum pump had failed resulting in loss of braking ability and expensive damage to the engine and other components. The manufacturer is aware of this issue. See: thieme, et al. V. General motors llc.

Vacuum pump that supplies vacuum to brake booster failed without any warnings beforehand leaving us without the ability to stop. Luckily was able to avoid an accident.

During my daily commute to work on the interstate the service break assist message came on my dash and when attempting to break the pedal was very hard, to the point where I had to push extremely hard and quickly realized I had to brake much much soon than normal to prevent hitting other vehicles. Sudden loss of brakes put me and other drivers at risk due to my near inability to slow down or stop and the sudden and unexpected nature of the event.

I am a [xxx] resident. While commuting to work in [xxx], my GMC Terrain experienced a sudden, catastrophic failure of the brake vacuum pump while traveling at highway speeds. When I attempted to slow down for the exit, the brake pedal instantly became extremely stiff and nearly impossible to depress. I realized I had suffered an absolute loss of power braking assist. To avoid a high-speed collision with heavy highway traffic, I was forced to deliberately steer onto the roadside rumble strips, relying on tire friction to slow the vehicle down. This severe near-miss left me terrified and distraught. Because the shoulder was narrow, my disabled vehicle was left partially protruding into the active roadway. Passing cars sped by so close that my vehicle was violently rocking, creating an incredibly unsafe situation. I was forced to call the state police for emergency assistance. They dispatched a trooper and a tow truck to remove me and the vehicle safely from the highway. The vehicle was towed to a mechanic in massachusetts. The mechanic discovered that the vacuum pump had internally exploded. This explosion sent catastrophic metal shards and debris directly into the engines oil galleys and oiling system. While the vehicle has 121,776 miles, this is not a normal wear-and-tear component failure. The brake vacuum pump suffered a catastrophic internal mechanical explosion at highway speeds, completely eliminating my ability to stop the vehicle. A mechanical component failure should never cause an immediate, life-threatening loss of brake control, regardless of mileage. This is a known, systemic engineering defect that is currently the subject of active federal class-action litigation (xxx v. General motors llc). This defect did not just cause an immediate life-threatening braking failure, it completely contaminated the oiling system, destroyed the entire engine, and rendered the vehicle a total loss requiring a full engine replacement. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552.

The brake vacuum pump had a catastrophic failure which resulted in the immediate loss of all brakes in the vehicle. I had the vehicle repaired only to find that gm has issued numerous repair bulletins to dealers and mechanics. This appears to be an issue known to them. As the vehicle was repaired, the parts are no longer available for inspection. This was a danger to me and others around me because I was traveling 60mph down hill with no means to slow or stop. I narrowly avoided an accident. There were no warning lamps before the incident. A warning lamp did come on after the loss of brakes but only after I attempted to brake.

While traveling on the highway in traffic, brakes became very stiff when depressed after attempting to slow down to exit. Was able to put full bodyweight into the brake pedal to slow enough to exit and navigate to the gas station right off the exit. Had to roll stop signs and unsafely navigate traffic because brakes were not working. Service brake system warning light came on after the incident.