Brake Master Cylinder problems of the 2015 GMC Sierra 1500

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.

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.

I pulled into a parking spot and lost the ability to stop my truck. The brakes locked up and I couldn't push down on the brake pedal hard enough to get the truck to stop. I was going slow enough to use the curb in the spot for it to stop me from hitting anything. I had my car towed to a repair shop and they confirmed that the brake vacuum pump failed and had to be replaced along with the master cylinder and because the vacuum pump was the initial point of failure, the repair was not covered under my warranty.

Hard brake pedal - "no brakes" first occurrence in paring lot 2016 timeframe . Was backing into a spot that was slightly downhill, no brakes , vehicle hit curb and stopped. Pulled forward no brake, eventually they came back . Complained to gm hotline - they responded with questions and I told them I took truck to dealer, I believe dealer replaced master cylinder second occurrence may 2017 driving on I-75 - 18 year old daughter driving on way home from college, traffic slowed and she said "I have no brakes, pedal wont move". She maneuvered to side of road, vehicle turned off and then back on, brakes came back and worked ok . Mentioned during oil change at serra Chevrolet, but since brakes were working they would not investigate third event - November 16-- at tail end of 8 hour drive returning from deer camp. Exit freeway and in stop and go traffic , on a downhill portion of road, the brake went hard . Got vehicle stopped and turned engine off and back on, brakes released. Contacted dealer about bringing truck in this week. Going to ed rinke dealership today Nov 24, I read article about the a faulty brake vacuum pump. This now makes sense. Please get this issue fixed.

Tl- the contact owns a 2015 GMC sierra. The contact stated upon getting a state inspection they failed due to master cylinder, vacuum pump, brake booster, and hose leak. The dealer was not contacted. The manufacturer was notified of the issue. The failure mileage was approximately 33,00. Kh.

When I press on the brakes, it feels as though the master cylinder is gone and it is the manual type drum brakes that has air in the line. It takes everything I have to press them and pray it stops!! the vehicle is always in motion when detecting this problem and seems to occur more repeatedly if the brakes are pump quickly in succession before applying brakes or when the brakes are pressed for an extended amount of time then you release and repress it want stop. Another issue is my lane id warning. When turned on at the button, it just beeps at me and shows service light. When I first took it in with the problem, the dealership called me and said all fixed, but it did it before I left the parking lot. They had my truck all day for the issue, put me out of a vehicle and then said they would need for extended time to repair but didn't know there was problem. How do you make that determination when you told me its repaired. I just turned it off and haven't used in 2 years.

Brakes became hard to depress and engage while vehicle was moving. Almost crashed vehicle. Afraid to drive. Brought to dealer. Said it was bad brake booster. After doing some research, found out should replace vacume pump, master cylinder, hose line, etc. , so I did. 44k miles, 3 year old truck, happened on /12/10/17 brought to dealer garber GMC in florida for $1300 repair on 12/11/2017. No warning signs when this happened. Very dangerous when brakes fail while vehicle is in motion.