[Vwdiesel] Alternator wires

[Sandy Cameron]

The fat red oneis juice to the battery, sometimes via the starter terminal,

The BLUE one  is the "startup" wire from the instrument panel, and draws
+12v battery power through the red lamp (when the ignition is on) to the
field until the alternator gets "excited" after which the lamp goes out, and
field power is generated in the alternator itself, passing through a
separate set 0f 3 diodes used only for that purpose, through the field, then
through the regulator, to ground. completing the field excitation exercise.

The "field" terminal rises to 12-14 volts so the lamp has 12v on both sides,
consequently'it goes out.

The THIN RED wire is the tachometer wire used by a tach, if you have one,
and the oil pressure "computer" on all diesels, tach or not.

Sandy