2020 GMC Terrain brakes problems

Filed Oct 27, 2026 · Brakes · 90,000 miles · OH

The contact owns a 2020 GMC Terrain. The contact stated that while driving 45 MPH, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The transmission then sputtered. The vehicle was uncontrollable, the brake pedal was depressed; however, the vehicle failed to stop as intended. The vehicle accelerated and drove through an intersection and the engine seized. The vehicle was towed to an independent mechanic where it was diagnosed with vacuum pump failure. The contact was informed that the vacuum pump needed to be replaced. The contact was advised to contact the dealer. The dealer was contacted and made aware of the failure. The contact was advised to contact the manufacturer. The manufacturer was contacted and made aware of the failure. The contact was advised to contact the federal safety agency Hotline to report the failure. The failure mileage was approximately 90,000.

Filed Sep 29, 2026 · Brakes · CT

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.

Filed Sep 23, 2026 · Brakes, Engine · NC

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.

Filed Aug 31, 2026 · Brakes · 92,000 miles · OR

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.

Filed Aug 23, 2026 · Brakes · MI

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.

Filed Aug 19, 2026 · Brakes, Engine · CT

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.

Filed Jul 30, 2026 · Brakes · PA

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.

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 Jul 18, 2026 · Brakes · IL

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.

Filed Jun 8, 2026 · Brakes, Engine · AL

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.