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Discussion Starter · #1 ·
Hey all,
67 mustang, wanted to upgrade alt cause im adding high end sound, and need more amps.
So i bought an alt, and it was a 1 wire, i tried hooking it up, but the charge post on back hit the engine ground, so i sent it back, and got a 3 wire, but i think its a 3G case, like Ford front Chryster back or something, but its external regulated, with main charge post, plus hookups through bracket on side.
I hooked it up, but couldnt get it to work. (Remove batt grnd, car died) then i realized i switched the 2 wires on side, so got em right now.
I am back to trying to use existing wiring, so even though i have a large gauge wire from charge post to battery, i had to hook up orig smaller gauge to that post, and it worked!... but i saw smoke, and realized one of the wires was being grounded, and it completely cooked it, all the way through, prob would caught on fire any moment, if left on... so now that wire, which appears to be the "S" off the alt is toast, and capped off, unhooked.
So now its working, as in providing a charge, but its reading 15.5v which is obviously too high...
I replaced regulator. Got old and new, either one, still at 15.5v
Any suggestions?
Appreciate any help thanks
 

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I'm pretty sure the 3G alternator is internally regulated and the S terminal is the voltage sensing terminal so it needs to be hooked up.

Good article here on hooking one up:

 

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Discussion Starter · #3 ·

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Scrolling further down it also says that a required part is the tuff stuff voltage regulator maybe that's the issue. I have a tuff stuff 1 wire alt and it idles 13.6 I believe. I did have to clock the case to eliminate the problem of positive hitting the block.
 

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That alternator is NOT externally regulated, like ALL modern alternators its internally regulated. That thing on the firewall that people call a regulator is NOT a regulator...its a switch that turns the internal regulator on and off once the alternator reaches the target voltage. Its important to understand this because what likely happened is that hooking it up wrong likely fried the actual internal voltage regulator. I recommend reading this for anyone swapping alternators:


This will tell you how they work and how you determine what type of alternator you have, as well as what each of your terminals actually do.

P.S. 1 wire alternators are pure garbage...their only advantage is easy hookup.
 
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