When running.
Current flows from the alternator through wire R6 through a 14 gage fusible link.
At the junction of the three links, current may divide. Voltage stays the same.
Current for the ignition and field flow through wires J1 (red) to the ignition switch. (There's probably a connector at the bottom of the steering column, but not shown in my schematic above)
From the switch it flows through the blue wire, dividing at the first spliced junction.
The portion going to the field goes up to the alternator. A smaller wire is spliced in for the Voltage Regulator to know the system voltage.
Current for the field goes through the alternator, out the green wire to the regulator, which, when allowing max current, lets it go directly to ground.