I was having a issue with over boost code 30fe over boost and 3100 boost disabled I tested all of the vacuum lines to make sure they are not leaking everything was fine there. Then the first time I tested the boost solenoid it held vacuum and I can hear it click if I put 12 volts to it does not matter witch side you put positive and negative and a couple of days later I tested the solenoid again it was one of the boost solenoids loosing pressure very quickly. The boost solenoids should hold pressure and then very slowly release pressure I hope this helps.