[tmataraza]

Originally Posted by gto4ben

Those voltages do not appear correct. If you look at the schematic in post #14, there is a resistor between terminals #3 and F. It should drop the voltage if there is a connection to the alternator. This is the same for both the 1115911 and 1115915 regulators when the ignition switch is in the run position. I did a quick check on my GTO to show this is the case (voltages lower at terminal F and at alternator F). Perhaps your connector to the regulator has a break or the connector to the 10DN alternator has a break. Typically due to the heat and age, I suspect the alternator connector or terminal.

You may be chasing two problems. The original regulator causing the 18V and a connection break when you tried replacing the regulator.

I think you're on to something. My alternator only has one wire connected to it, blue, and there is no wire missing or anything and the Voltage Regulator has two wires, blue and black, with the blue carrying the 12v. I thought the black was just going to ground, but does the schematic show that the F on regulator and F on alternator need to be wired together?