Fusible link melted!

If you are saying bypass the meter under the hood, but leave the ammeter untouched, that is MAYBE OK if the ammeter circuit is OK. But if the ammeter happens to be part of the problem, then no.

Actually, some of the cars used a sort of a "partial" bypass which acted as an external shunt for the ammeter. I would guess the bypass might be, say, a no 12 wire, so part of the current went through the bypass, and part through the ammeter