Wacked Out Gauges
Alt gauge starts barely on the charging side & within a couple of minutes shows discharging the balance of running. No notice of slowing or dead battery.
As mentioned above the "alternator gage" is completely seperate from the others. Assuming the wiring hasn't been screwed with, its wired directly into the battery feed. If its centered when the engine is off ( all lights off including dome and brake lights) then it should be centered when the battery is completely charged. Anything else indicates battery charging or somebody added electrical something to the battery side of the ammeter.
Battery charging could be due to low or damaged battery, excessivly high alternator output voltage, poor alternator output, or resistance in the the alternator output line. Quick way to narrow that down with minmal tools is:
1 Engine off, measure battery voltage.
2. During starting measure battery voltage.
3. During fast idle idle or at 1250, measure battery voltage AND measure output voltage at the alternator. If the voltages are different, measure the votlage at the regulator input connection (blue wire). Note the alternator gage reading. (scale is 40 amps discharge to 40 amps charging, estimate from that).
4. At slow idle measure battery voltage AND measure output voltage at the alternator. If the voltages are different, measure the votlage at the regulator input connection (blue wire). Note the alternator gage reading.
Write down the results and we can tell you what they add up to. Please don't guestimate.