One problem related to brake light on has been reported for the 2017 GMC Sierra. The most recently reported issues are listed below.
Was driving my 2017 GMC Sierra with my wife and young son. I went to stop at a red light and had no brakes. The brake was very hard to push and made a funny clicking noise when I shoved it to the floor. I was barely able to avoid a collision and pull into a parking lot. I noticed then, that the service brake assist light was on. The truck gave no prior warning that anything was wrong. This was a very scary situation that could have resulted in a terrible accident.