Without knowing the PV's cluster wiring, about all I can do is describe the '75 240 for you, so you can compare the two.

1) The Exciter current to Alternator post 61 (or D+) starts from the Ignition Switch and goes to Fuses 3-4-5 common input side. From Fuse 5 it goes to the Hazard/Signal flasher, and to the instrument cluster as the main +12V supply. This +12 at the cluster is available to several Warning lights, so any that are grounded will light up.

2) The "Charge" warning bulb ground side wire goes to Alternator 61/D+, then thru the brushes & commutator, and finally the Alternator grounding wire. That single bulb current might be enough to pre-exite the alternator, but actually there's more.

3) To provide for complete Bulb-Testing, 3 more bulbs* (not normally grounded at Key On) are diode-connected to the Charge bulb's ground side. So they light up too, and their current adds to the pre-exitation current.

4) Once the alternator puts out voltage, the 61/D+ terminal is no longer a ground, but rises to the Alternator B+ output level. So with +12V on each side, the Charge bulb goes off, as do the other 3, unless/until their normal ground side is made.

* Diode-connected bulbs are:

• Parking Brake
• Brake Failure
• Bulb Failure

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.