Controller and all valves are Rain Bird brand. Controller is testing normal at 24 volts ac. No zone will operate in either manual or auto mode unless I disconnect the black wire supply from the controller to the black wire on the master valve solenoid and open the valve flush then all zones will run as programmed or in manual control mode. I would like to test the supply wires from the controller to the master valve to eliminate the possibility of one being broken. I believe I do by disconnecting the common (white) and, in my case, black wire from the controller and using a multimeter set to the lowest ac voltage setting that will allow me to see if there are 24 volts ac getting to the master valve. My confusion is which white (common) wire goes to the master valve. I have not seen two common wires attached to a Rain Bird controller in any trouble shooting video I have watched to date. Any input is appreciated.