[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?

[gto4ben]

The new regulator is equivalent to a 1119519 which was used with 63A alternators and idiot lights. The giveaway is the diode which was installed to reduce contact wear.

Moving the wire from terminal #3 to terminal #4 bypasses the relay and will work/

[george kujanski]

If it stays at 14.7 or so at higher RPM you are good to go. If it still goes hi, there is something wrong with the wire going to terminal 4 on the reg or a bad reg body ground. That wire provides sense voltage for the reg.

George

[gto4ben]

...does the schematic show that the F on regulator and F on alternator need to be wired together?

Yes, the Service Manual shows the dark blue wire ties the F on the alternator and regulator together.

[tmataraza]

All this time the wire has been missing and I had no idea! The connector that holds the wire into the alternator doesnt even have any wire coming from it! Its just a two wire connector with only one wire coming from it.

Thank you everyone! And I got my shop manual today! Very pleased! I hope to read up and learn about this stuff now. I will also rewire my F to F connection on Alt and VR. No idea what happened there. I wonder now if my old regulator never was bad to begin with?? It was only at the higher RPM that over voltage was occurring.

[tmataraza]

So here is the alternator diagram that I found online. The alternator itself has no markings, and only 2 wires coming from it. Looks like my blue wire is F and that is connected to F on the voltage regulator. I have no ground coming off the alternator and the black wire on the voltage regulator is going somewhere, but its taped and tied and I have not been able to trace it yet. Im guessing from the diagram on the book and provided by GTO4Ben, that I need to check the grounds on the VR and possibly run a wire to ground the alternator.

[gto4ben]

It's strange that the plastic plug is missing on the alternator. It's a potential short to ground and will shorten the regulator life if that happens. They do sell pigtails to replace the missing connector.

The alternator is grounded through its case. A separate ground wire from the alternator case to engine and body grounds isn't needed provided the ground straps from the back of the engine to the firewall are still there.

There is a black with white stripe wire from the regulator to the bulkhead connector. It eventually get's to the ignition switch for power. The only solid black wire is the interior of the car going to the ammeter.

[stellar]

Having only one wire in the alt plug is correct and it goes to the F terminal on the reg. The black wire is ign, on off with the key going to ign (#4) on the reg. That is all his charging system requires. The blank connection in the alt plug would normally go to the #2 terminal of the reg, but is not used . That is why you will see the #2 reg terminal missing on his application.

[tmataraza]

Originally Posted by gto4ben

It's strange that the plastic plug is missing on the alternator. It's a potential short to ground and will shorten the regulator life if that happens. They do sell pigtails to replace the missing connector.

The alternator is grounded through its case. A separate ground wire from the alternator case to engine and body grounds isn't needed provided the ground straps from the back of the engine to the firewall are still there.

There is a black with white stripe wire from the regulator to the bulkhead connector. It eventually get's to the ignition switch for power. The only solid black wire is the interior of the car going to the ammeter.

Alright. So I traced wires. The black wire on the regulator is black w/ white stripe and is the ignition. With the car running, I have 14.5-14.7v on the battery terminals. With the red of the voltmeter on the red of the battery, I moved my black on the voltmeter to the unpainted body, the engine block, and the alternator casing, in which all 3 locations had 14.4-14.7v. I guess Im good now. I found out tonight that I had won a previous bid on another regulator (part# 1119511) so I might try to swap that in ($15 vs $75 rockauto part). Now I know what Im looking for and thinking that I need a different battery gauge since mine shows me anything over 14v is red zone. Aesthetics and OCD wont let that live, even if 14.4 - 16v is normal per the shop manual.

Last question. Would fixing all this and having the correct voltage regulator fix the previous incident of my ammeter gauge not working? It was constantly bouncing all the time, especially at stop lights, and I thought it was just broken when I always had 13+ volts on the battery at idle.

Thank you again for everything!

[gto4ben]

Very likely. If your alternator voltage is higher than 12.6V, it's charging the battery and the ammeter should read in the C (charge). The amount of charging will vary depending on RPM, load, and temperature. If you have AC and headlamps ON, it may dip into the D (discharge) zone at idle but will start charging once you get going. There shouldn't be any bouncing when everything is normal.

[tmataraza]

Thanks. I'll plug it back in and see what happens. I do think I had a grounding issue in general because my headlights and dash lights were dim and just other oddities. I thought all things full due to age, but In my troubleshooting 4 different voltage regulators, I also replaced the negative terminal on my battery and moved it to the frame from the engine block. The block is also grounded to the frame, so it might have been the solution to a multitude of issues