Powermaster brake help!
 

Hello. I am new to this forum and am hoping someone can help. I have a 91 Cutlass Supreme Convertible with a Powermaster III brake system that is giving me fits. I never know when I will have brakes; at times it seems to work perfect, other times my brake and/or abs lights burn (or flash) and I have diminished brakes. A couple of times I have lost all brake. Does anyone know anything about these systems? Any help would be greatly appreciated.