The question about the two vs three prongs on the electronic voltage regulators from 1969 interested me. I just got out my 1969 service manual to see what I could figure out.
It shows three wires for the Imperial voltage regulator. One (R3 18DGN) goes directly to the alternator. This is the right hand pin on the voltage regulator.
The middle pin on the voltage regulator (R6 12BK) goes to the other lead from the voltage regulator and goes into various circuits in the instrument panel.
The remaining left pin on the voltage regulator (J2D 18DBL), which appears to be missing in the two pin version of the voltage regulator, goes to one connection on the ballast resistor which also is connected to various circuits from the instrument panel.
Thus it appears that the extra line is not a redundant ground, but a redundant live wire to the ballast resistor.
Is this correct?
Fred Joslin
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