The power comes from the center of the outlet and the power wire connects to there. The ground then goes to the side of the outlet. Since I don't have that van to look at, here are possibles. That ground clip on the inside goes all the way through the outlet and touches the metal of the dash to complete the circuit, and that connection could be bad. That ground clip on the inside goes out and has a ground wire connected to it that goes to a ground point on the firewall, and that connection could be bad.