2nd Fried Voltage Reg? Wiring issues....

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Jun 22, 2016
San DIego
Hey all, Happy 4th!
I just picked up my 68 FJ and am working on getting up her up and running well. It initially wasn't charging the battery, so I got a new voltage regulator. After installing the new VR, the problem wasn't solved. I then looked back over everything and realized two important factors:

1. There was no positive cable going from the alternator to the battery to charge it.
2. There was no external ground going from the alternator to the chassis.

So.... I fixed both of those issues, now it seems to be charging, but not when the car revs. When the car revs, the voltage actually drops.

The FJ is running a bit rough now too, where it used to just purr.

The turn signal fuse is continuing to blow as soon as the ignition key is turned. With a multi-meter, I measured the current between the fuse connection points, sure enough, it shows the full battery voltage at that fuse. The fuse, which is supplied by power at once side and has the other side going to 1: the turn signal flasher and 2: the Voltage Regulator Ignition terminal.

So it appears the Voltage regulator is grounded out and the VR is allowing the ground to go back to the fuse box, blowing the fuse constantly.

I separated the two wires going to the receiving end of the fuse box, where the fuse was blowing to see if one wire was the problem versus the other. The VR wire read 12.8V or something similar and the turn signal flasher read 9.2V or something close. So they were both grounded out.

I then wired a new test wire through the firewall to hook up to the IGN VR terminal and connected it to the fuse box to see if the wires themselves were the issue. The fuse box gave the same reading showing over 12v between the fuse box terminals.

So I'm thinking that running the car with the alternator pushing a ton of electricity to the VR when the alternator wasn't properly hooked up fried the VR for the second time.

I tried to test the VR by itself, but I'm afraid I don't really have the know how. I applied ground at the E terminal, applied 12.8V directly from the battery to the ign terminal and the F terminal was putting out the exact same voltage. I don't know if that means any thing, or where I'd go from there.

So I ordered a new VR, hoping that that will be the fix. I'm open to any input!

I figured others may have the same issue I was having, so I'd write up the issues I'm facing.

I'll update as soon as the part comes and I slap it in!

The B terminal on the alternator goes through the ammeter and then to the battery.
This might help.

Ah! I see that now. Wonder where that wire went! I'll have to track down why there isn't a wire going to the battery. Maybe that's loose and ground out somewhere.

The white/blue wire goes into the harness and likely to ammeter, but I need to find the wire that's supposed to go to the battery.

Right now I just have a wire directly from the alternator to the battery to charge it.

Thanks for the info and diagram!
So I went back to my owners manual wiring diagram to see why I didn't see that initially. It's there, but the power goes to the battery through the starter. It is a white power cable. That cable is there and connected to the same terminal on the starter that comes from the battery, so that wiring is all there and correct.

I assume I should remove the wire that comes directly from the alternator to the positive side of the battery?

I'm so close to having an auto electrician make this work, but this system is so
Bare bones, I should be able to do this!

Thanks for your help!
You got this. It's obvious you've got the smarts and are keenly detail oriented.

If you haven't pulled your gauge cluster, you may want to have a look behind it. Your Ampmeter should have white on + and WL on on -. L = light blue. Also, where your WL connects to starter + you can add a @Coolerman fusible link. He just got me setup on that program! It's a good piece of mind to have that extra bit of protection. If want to read some good wiring discussions, search for stuff he's posted.

A wire wheel on a dremel comes in handy when cleaning up electrical connectors. They make a flexible attachment, sorta like what dentists use. I've found mine well worth the investment.


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