Need some help please.  My girlfriend drives a 1993 Chevy 3500 diesel.
Dually, 5-speed, dual batteries.   The gauges keep acting up.  It calls for
a 20 amp fuse, which keeps blowing.  I have gone as large as a 30 amp, but
it also blows in a few seconds.  How do I go about troubleshooting the gauge
circuit?  Recently, the battery was going dead. Alternator was putting out
less then 12 volts( with a blown fuse) so I replaced the alternator.
Getting 13.4 now.  Thanks, Chief