you need to find out where the other end of that wire goes and determine if it should be hooked to anything, the shop manual wiring diagram is a good start
from feeble memory, there should be a wire from the starter terminal that the battery + hooks to, that goes to one side of the ammeter - from the same post on the ammeter there's a wire to the ign sw that supplies power to accesory stuff when the key is on only
Bill
