GMC Terrain spongy pedal problems

Filed Oct 29, 2026 · Brakes, Transmission · GA

While driving, I was getting ready to turn into the left lane then I noticed the brake pedal was hard as a rock so I immediately pulled over into a community. I knew it was safe I could barely stop the vehicle because the brake pedal was not giving at all, but eventually, I was able to stop I believe if the terrain wasn’t uphill, I wouldn’t have been able to stop my husband came and assisted with driving the vehicle to the dealership at a very low speed and hazard lights, which was about 20 miles away. This was very scary, but we made it since then the dealership has diagnosed it and it has something to do with brake assist power pump failure, which is documented in a class action lawsuit in Michigan with the same exact problem I’m in the process of getting it fixed down to the camshaft still waiting on final expenses, which I’m sure will be in the thousands we contact the GM to try to get some help with the repairs and they offer us a $350 to help out only if our all change record are acceptable not acknowledging the faulty mechanism power vacuum pump that created all of this

Filed Sep 17, 2026 · Brakes, Engine · KY

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.

Filed Aug 21, 2026 · Brakes, Electrical · PA

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.

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 Jul 23, 2026 · Brakes, Engine · NH

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.

Filed Mar 28, 2026 · Brakes · VA

Brake assist light came on and brake pedal became stiff/hard to push. Vehicle struggled to brake. Replaced brake pads and checked brake fluid. Brakes still inoperable. Check engine light came on for vacuum pump. When replacing pump, metal shards and pieces were falling out when original was removed. Once replacement was installed vehicle began hesitating to start and run.

Filed Feb 9, 2026 · Brakes, Engine · 1,126 miles · AL

The contact owns a 2025 GMC Terrain. The contact stated that while his wife was driving approximately 40 MPH on wet roads, the brake pedal was depressed, but the brake pedal was stiff, preventing the vehicle from slowing down as intended. There were several unknown warning lights illuminated during the failure. The accelerator pedal was released, and the vehicle rolled to a stop. The vehicle was turned off and restarted, but the check engine warning light remained illuminated. The vehicle was pulled over to the side of the road and turned off. The vehicle was then towed to a dealer, where it was diagnosed, and determined that the brake control module needed to be replaced. The vehicle was repaired, but the failure reoccurred approximately 7 months and 2 weeks later. The manufacturer was notified of the failure. The failure mileage was approximately 1,126.

Filed Dec 16, 2025 · Brakes · OH

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.

Filed Jun 17, 2025 · Brakes, Engine · NY

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.

Filed May 13, 2025 · Brakes, Engine · 10 miles · NY

The contact owns a 2024 GMC Terrain. The contact stated that while driving at various speeds, the vehicle was hesitating while accelerating. The contact stated that the vehicle was stalling, and the brake pedal was spongy. The vehicle was taken to the local dealer on several occasions, but the failure was not duplicated. The vehicle was not repaired. The contact stated that the failure persisted. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was 10.