The Proximity pin on SAE J1772 and proximity pilot on IEC Type 2 connector signal to the vehicle that the charge handle is inserted.
Proximity on SAE J1772 connectors can ne tested by measuring resistance from the proximity pin to ground. The resistance should be 150 ohms when the button is not pressed and 480 ohms when the button is pressed.
Ensure when connecting to the vehicle the button clicks BOTH when pressing the button down and when releasing on the vehicle.
Proximity Pilot PP on IEC Type 2 "Mennekes" Style plugs provide a set resistance from the PP pin to ground.
With a multi meter measure from the PP pin to the Ground Pin in the Type 2 handle.