The green wire to the VR gets 12 volts when Its unhooked from the VR. When connected it’s at 6 volts. One thing I don’t understand is why it changes to 6 volts when connected and 12 volts when not connected
Voltage only drops when there is current flowing. When you disconnect the green wire, the electricity can not flow to ground.
Picture voltage like water behind a dam with various passages feeding off, but all closed. Its potential power, and until it moves, it has the same potential all over.
Another way to picture it is like air pressure. If you have an airpump and tank, the battery is like a pressurized tank, and the pump is like the alternator. Voltage is like the pressure inside. Air pressure outside the tank is like ground voltage. The pressure inside the tank would love to get outside, but it can't until there is a route.
Disconnecting the green wire is like disconnecting an air hose with a shutoff coupling. The pressure in the hose can't get out, and is the same as in the tank, or the pump, whichever is higher.