I would have guessed it would be either the ammeter (P terminal) or the alternator terminal (J terminal) as they are connected to the battery directly. If you look at your wiring diagram, the alternator terminal leads to a splice in the wiring harness in the passenger compartment that feeds:

1) Ammeter
2) Ignition switch
3) Headlights
4) Fuse panel (always energized circuits)

It looks like it's one of them.