After a fire.....

And there's your short ,
So tracing back to the Battery that wire goes through the B pin in the Bulkhead connector to the splice on its way to the Ammeter , then through the ammeter to the Z pin in the bulkhead connector to the Starter Relay Bat terminal , then to the Battery .
On its way its bundled with most of the under dash wiring and the resulting Fire .

If it had a fusible link It would be on the engine compartment side of the Z pin in the bulkhead connector and only burned that link thus saving the wiring and no fire .