On a 12 volt ignition with ballast resistor you should see 12 volts on the coil + with the points open and about 6 volts with the points closed unless the starter is cranking. With the starter cranking, you will see the same voltage at the coil + as at the starter with points open or closed (will be less than 12 v due to starter drag). The coil - will be 12 v points open and 0 v points closed.