AUX batteries (4-six volt) do not register anything on the cabinet readout. I cleaned all the terminals on the 6volts, still nothing on cabinet meter. If I touch volt meter to + and - of each battery I get about 6.5 VDC.
This is normal..6.5 at Each battery shows that each battery has a full charge. You have 2 batteries tied together making 2 banks of 12V. They are then fed into the coach as a 12V circuit. If you have nothing at the cabinet meter, there could be a battery cutoff switch that has been turned to the off position.