Volt Meter

What would cause my volt meter to read only 10 volts? I did not notice what it read before the stereo got hooked up back in the spring. The amp is grounded to one of the batteries, would this cause it to only read 10 volts?

Check you voltage with a decent multimeter.
My guage under reads by a couple of volts and my mates in his seray over reads by a couple.

It could very well be reading 10 volts, or it may not be reading the actual voltage. Either way start with a volt/ohm meter and test the wiring circuit at the gauge, and go from there. Often times what happens is the wire going to the dash and accessories is too small, and the voltage drops. Adding in either a larger size wire or a relay triggered how ever you want.