VDO Voltage gauge now reading low volts...
 

Any links handy to help me diagnose this voltage problem...last time on the lake the voltage gauge suddenly started reading a hair less than 12 volts...I did replace the alternator already, the batteries are always on a maintainer when parked, I got the same reading on the gauge terminals as shown on the face...with all power off both batteries just metered 13.06v.
Update...found a short under dash. Now good. Thanks.