Well, ive been having some problems with my 1987 buick grand national powermaster brake system, as many people do, and I have been looking everywhere for similar problems, but I finally caved and decided to ask someone here. So, whenever I turn the ignition on, the motor pump doesnt stop running, and ive noticed that the fluid in the reservoir doesnt get pumped out, it just stays at one level. The brake light also doesnt turn off at all, even when the engine is on. We tried putting on another switch that we had from another powermaster, and the pump would run properly, but there would be this hissing sound coming from around the accumulator and the master cylinder. I really hope someone can help me out, these brake systems are so strange to diagnose. If anyone has any questions I would be happy to answer.