I finally teed in my boost gauge in my '87 190DT. I put it in past the switchover valve. I saw a whopping 0 lbs of boost then. Well, I unplugged the switchover valve and everything was good. Got a smooth 0-15lbs of boost. So my question is, why is the switchover valve constantly energized when the key is on? I tried to search for it but could not find anything.