Welcome. I will try my best to help you and in order to do that, I need you to describe as best you can because I only know as much about your problem as you have told me in your post, so my answer will be based on what you have posted. Please feel free to reply as needed.
This is one of the front brake calipers? If so then a bad brake hose can act as a check valve when the inside lining fails.
Chevy Technician
GM Grand Master Technician 2007. 9 years Automotive experience, 7 years with GM. Just Answer Mentor