You should have 12v at the outgoing terminal and at the GP connector when you turn the key on and hear the thud. If no thud, more than likely the solenoid is bad or you have other issues with the controller. If you hear a thud and no 12v outgoing, the solenoid is bad.
Just an FYI, the solenoid is pretty cheap to replace if you need to but search on which one you need. I believe it is a constant duty isolated ground solenoid. Someone can confirm the number or you can search it, pretty common problem. Don't overlook the control system.