Get yourself two six volt batteries.
Get two 15 ohm or three 10 ohm resistors.
Put batteries and gage and sender on bench. Connect batteries in series but leave a connection between them to get six volt.
Then using proper polarity connect gage to one side of battery then otehr side to sender and ground of sender to other side of battery. Would do six volt first. See if works. Now replace sender with resistor if 10 ohm should give 1/3 scale if 15 one half. If works with partial resistance ie 10 or 15 and works with full ie 30 you have a 6 volt setup. IF not then connect to 12 and try again.
Dan Bentler
