Ammeter Resistance and Voltage drop

There are three big "points" in the system that are suspect........the bulkhead terminals for both the RED and BLACK ammeter wires, and the ammeter connections (wires and terminals) and the ammeter itself.

The RED and BLACK terminals right at the ammeter can fail, and the INTERNALS of the ammeter can fail, here is how.

The "guts" of an ammeter is just a brass strip that forms a shunt of sorts and generates the magnetic field that causes the needle to deflect. At the ammeter terminals, they are a sandwitch, of the bolts, washers, etc, all compressed together UNTIL (on some models) that high current can loosen the insulating washers, and on plastic dashes, soften the dash housing, as well as the usual corrosion. Part of the fix, other than eliminating the ammeter, is to pull it apart and solder or silver braze the "shunt" to the studs.

I would make more checks if you can. See if you can clip onto the red (battery) side of the ammeter and compare that reading, then clip into the RED and BLACK terminals at the engine bay side of the bulkhead connector and compare those readings.

I LIKE ammeters, but many of us have just thrown in the towel and gone to voltmeter. There is an old thread about doing that

https://www.forabodiesonly.com/mopar/threads/ammeter-to-voltmeter-who-does-it.119480/
Also if you have not, read the MAD article on the how and why of ammeter / bulkhead connector failure.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml
Most of us here do not do it that way. "Fix" the bulkhead, bolt the ammeter connectors together, and then run a fused/ breakered BIG wire from battery + direct to alternator output.

Crackedback, on here, does or did make these