2018 GMC Terrain brakes problems

Filed Oct 14, 2026 · Brakes, Engine · IN

On XXX while driving my 2018 GMC Terrain SLE 1.5L turbo on the highway at approximately 70 MPH near [XXX]. I experienced a sudden loss of power brake assist without any prior dashboard warning lights or messages. I was traveling with children to [XXX] 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 XXX, 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. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Sep 30, 2026 · Brakes, Engine · NY

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.

Filed Sep 14, 2026 · Brakes · 116,000 miles · NJ

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.

Filed Aug 24, 2026 · Brakes, Engine · AL

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.

Filed Aug 21, 2026 · Brakes · 117,000 miles · WV

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 federal safety agency Hotline for assistance. The vehicle was not yet repaired. The failure mileage was approximately 117,000.

Filed Aug 10, 2026 · Brakes, Engine · MI

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.

Filed Aug 3, 2026 · Brakes · 95,300 miles · IL

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.

Filed Jul 22, 2026 · Brakes · PA

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.

Filed Jul 17, 2026 · Brakes, Driver assistance · PA

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)

Filed Jun 5, 2026 · Brakes · MO

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.