Brake vacuum pump booster. First started when driving under 5 mph. The brakes were hard to push down and would not stop the truck properly. Did this for approximately 3 months. Then driving getting off the interstate and applied brakes going 60 mph the brakes would not work. Could barley stop. Same issue has when driving slow. Now the brakes will not work at any speed. They truck is undrivable until it gets fixed.

- Prairieville, LA, USA

At low speed and on a number of occasions, the brakes have seemed to lose power and it required a lot of brake pressure to stop the vehicle and avoid hitting another vehicle, my garage, etc. It had been happening intermittently over the past month or so. Went in to the dealer and they replaced the vacuum pump at a cost of approx $600.

- Scottsdale, AZ, USA

Very difficult to stop the truck while going at a low rate of speed 5 to 10 mph. Had to forcefully apply pressure to the brake pedal to get it to stop still required more stopping distance. Brakes did not become fully functional until after placing the vehicle in park and shutting the vehicle down waiting for approximately 15 minutes. Restarted the vehicle and brake were functioning properly. This event occured at approximately 46,000 miles on the vehicle. Following day brought the truck into the local GMC dealer and verified that the truck has a braking problem found a leaking brake booster and master cylinder.

- Port Angeles, WA, USA

Vacuum pump failed at 58000 miles. Lost brake assist at parking lot speeds. Could have caused an accident.

- Fontana, WI, USA

The brakes at a low rate of speed (1-10 mph) partially gives out which prolongs the stopping distance of the vehicle. It seems as though the ABS kicks in but for no reason. Must strongly push down on the pedal to get vehicle to stop, which still requires additional stopping distance. Has occurred sporadically from mid-2018 to March 2019. No resolution through dealership.

- West Point, NY, USA

Brakes completely failed. Replaced brakes on all 4 wheels, but to no avail. Then replaced the master cylinder and still no brakes. My fence pole and mailbox stopped my vehicle.

- Albuquerque, NM, USA

When I first got the truck the brakes operated perfectly fine after about three days the brakes on the front of the truck would lock up while I was driving and would not release. After two sets of calipers two sets of brake pads a set of rotors a two weeks go by with the mechanic trying to figure out what is wrong with this truck. They then replace the brake master cylinder, there was no improvement. Turns out to be the brake booster had failed along with the hydraulic ABS control unit. There were no warning lights on whatsoever the whole entire time the brakes were locked up the ABS light didn't come on until the brake booster was replaced indicating that the ABS control unit was also bad. Now I am experiencing a ticking coming from the engine. The ticking occurs at idle end as the throttle is being activated. However the local dealership has refused to give me any information as of why it could be making this ticking noise or is just unwilling to say anything.

- Paw Paw, MI, USA

I pushed on the brakes when slowly pulling into a parking spot and the brakes got squishy and barely stopped before I hit another parked car. This happened a few times before I got the vehicle home. Then a message popped up that said "service brake assist system". I took the truck in and they said they would need to replace the vacuum pump and 2 belts.

- Collinsville, OK, USA

Brake assist warning light came on with hard brake pedal at low speed braking. Does not happen ofter. Brought to dealer and had tested with no trouble found. Dealer said no recalls or service bulletins on issue.

- Metairie, LA, USA

Brakes not working. Had to replace the vacuum pump belt, brake booster vacuum pump, and ac belt. Cost $573.86. Vehicle only has 40K miles. Very dangerous, vehicle would not stop when applying brakes

- Berkley, MA, USA

At low speeds breaking becomes extremely difficult leading to longer stopping distance.

- Northglenn, CO, USA

Brakes fade at low speeds, vehicle continues to travel while the brakes are applied. Hard brake pedal pressure must be applied to stop.

- Wildomar, CA, USA

Brake pedal or that increased effort is needed to depress the brake pedal. Also, in some cases a tick or ticking noise may be heard, which may sound like an exhaust manifold leak.

- Spring, TX, USA

I was on a major highway traveling when the traffice became stop and go. As I was traveling in heavy traffic for about 5 minutes, my brake became stiff and would not allow me to stop as normal. I was able to stop just short of rear-ending the vehicle in front of me, however it was merely by inches. Considerations : I was on a slight decline and my vehicle has start assist where the brake pedal remains stiff when in effect, it felt like this activated. I continued to increase pressure through which I thought I heard the ABS activate and the vehicle stopped.

- Littleton, CO, USA

At low speeds break pedal will not depress and I have a hard time stopping the truck. I almost hit a car yesterday and after doing some research found that the vacuum pump failure is a known problem. This is extremely scary and dangerous. Someone could easily hit a pedestrian. My truck has less than 50,000 miles, which seems to be the average for this problem.

- Elk Horn, KY, USA

The contact owns a 2015 GMC Sierra 1500. The contact stated that when the brake pedal was applied, the vehicle failed to respond. The contact had to apply force to the brake pedal to stop the vehicle. Laura Buick GMC (903 N bluff rd, collinsville, il 62234, (618) 344-0121) diagnosed that the brake vacuum pump may need to be replaced. The vehicle was not repaired. The contact was uncertain if the failure was related to NHTSA campaign number: 14V339000 (steering, service brakes, hydraulic). The manufacturer was notified of the failure. The VIN and failure mileage were not available.

- Portageville, MO, USA

Brake pedal goes soft and can hit the floor on occasion. Mostly happens with in reverse. 40K miles. Also transmission shifts are erratic. RPM can shoot up between shifts.

- Saint Charles, IL, USA

Several times at low speed maneuvering the brake pedal became hard, required increased effort to depress, and braking distances were increased. Occurs randomly and without warning. No accidents yet, but several close calls. Vehicle has only 44,000 miles.

- Ottoville, OH, USA

At slow speeds the brake assist does not work. Requires much more effort to stop vehicle. Seems related to faulty vacuum pump as mentioned by ohters on internet forums.

- Gloucester, MA, USA

When applying brakes after first push the pedal gets hard and doesn't stop hardly. Does it either going forward or reverse. Has happened numerous times since truck was bought new.

- Muskegon, MI, USA