I think what you are saying is that you think you can hear the solenoid in the valve body working when powered through the switch. If this is true then I would initially suspect that your modulator is either not adjusted properly (if its an adjustable unit) or the wrong modulator. Here is a link to adjusting the modulator. https://www.chevelles.com/threads/how-much-to-adjust-vacuum-modulator.146481/
