Ammeter heating up.........

I actually like ammeters. And properly done they can be safe and useful. Unfortunately, "most" of the factory external shunt designs were done like everything else....to save a nickel. Both Ferd, Mopar, and probably GM used the harness as the shunt

What this means is they are "numb."

On my two earlier (87 and 86) Rangers you had to stare intently at it to see if the headlights moved the needle.