Two problems related to brake light on have been reported for the 2015 GMC Sierra 1500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2015 GMC Sierra 1500 based on all problems reported for the 2015 Sierra 1500.
Experienced an unusual reaction to breaking. A few days later I had brake warning lights on the dash. Took the vehicle to the dealer and they had to replace the cylinder brake master and the brake booster and add new fluid. Which I paid for. Now I see there may be other issues as there are other complaints you're investigating. I want to put mine on record.
I was driving down i20 in dallas in rush hour traffic, the traffic was heavy but moving at 70 miles an hour. I saw brake lights in from of me, when I pressed the brake to slow down the brake pedal was hard, I could not press it with one foot and I could not slow down. I finally was able to slow down by putting both feet on the pedal with all my weight it felt like it was forever before I was able to slow down. I thought I was going to be unable to stop. I drove another 15 minutes going very slow and scared. Parked my truck in the drive and had a tow truck pull it to the dealership closest to my house. My truck only has 58,000. I really was scared for my life if you have ever driven in rush hour dallas traffic you understand . I could have lost my life or be seriously injured. The dealership told me today they had not heard of this issue. The dealership said they doubt GMC can do anything about the problem. The service department said was a vacuum pump on the breaks. I looked on line and others have reported this same issue. I could have been killed. Still shaking over the incident . I hope this problem is addressed before someone is killed.