i was wondering what is the easiest or best way to check a volt gauge that is not installed. the one that i got with my u-14 gauges is reading high so i want to make sure the gauge is accurate, by comparing it to another
thanks

connect it to a battery, and connect a digital volt meter (test meter) also, and see if the gage agrees with the DVM

I would also test it like jforb stated and if you want to go further with the test still have a DVM hooked up in parallel with the volt gauge and then hook it up to a variable output DC source. This way you could see how the gauge reads at lower and higher input voltages.
Jim