Volt meter hook up

[Highbanked Hauler]

 got a sunpro volt meter for temporary  laying on the floor   I have 12.5 volts going to the side with the rubber insulator and the other side to a good ground I can't see the wires being switched side for side as it would be uninsulated .. Is there Any way to test the meter itself  It has the two mounting poles on the back. ideas?

[Nacho-RT74]

usually I make an OHMN/continuity test between leads