hey del

The GM alternators are the "Motorola design", and is in my 80's M-B cars. The most confusing part is the "excite" wire (post 4). I call it the "boot it up" wire. It initially needs a small current thru that wire, usually from a dash lamp, to get the internal Vreg to self-power. My M-B manual says if the BATT bulb doesn't initally light, to drive immediately to the dealer, presumably for an emergency bulb replacement (I bet dealers loved that). Actually, 3 bulbs on my dash provide boot-up current. At higher rpm, residual magnetism in old alternators can generate enough to boot it up (even w/ bulbs blown). After I changed to dash LED's, it doesn't boot at idle, but rev'ing slightly works. The bulbs go out once the alternator Vreg generates power, which also serves also as a "bulb test" function.