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anybody have a 3g diagram

MonsterBIlly

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Dec 17, 2015
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456
Looking for a 3g alt wiring diagram. I need to check mine becuase i am having a few issues.
 

DirtDonk

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Nov 3, 2003
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Steve83 here has some good updated ones on his SuperMotors site as well.
What are your issues?

Paul
 

DirtDonk

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I ask that because in your other thread you say you have a 1-wire alternator. I didn't think Powermaster made a 1-wire 3g?

Paul
 
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MonsterBIlly

MonsterBIlly

Sr. Member
Joined
Dec 17, 2015
Messages
456
Paul,
Im sorry you are correct. I had my termanology wrong. I am looking for instructions when installing a one wire alt. I know it seems brainless but i removed my voltage regulator and the large black yellow woir with what look like a fusible link.

My bronco charges when idling now but under load it shows low voltage. It may be too big of a draw for the fuel pump though.

Im not sure if my prob is the fuel pump draining or another wiring issue.
 

DirtDonk

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There is nothing common on a Bronco that can task a 100 amp alternator. Certainly not a fuel pump or heater motor. You'd have to turn everything on and add a kicking amp for your stereo to drag it down if everything was working as expected.
A fuel pump is just maybe 2-5 amps. The whole engine running with EFI and pump and such is probably drawing less than 15 amps total. Just guessing of course, and have not bothered to add everything up for an accurate tally, but that generalization should get you in the ballpark.

An electric cooling fan can be a huge draw (or not) and a winch being operated can easily tap out a good alternator. But normal use? Nope. So something is definitely wrong with something.
I'm not sure how to test a 1-wire, but there might actually be a test port where you insert a metal rod/screwdriver/widget thingy to "full-field" it for testing. But to be accurate you'd still need an inductive ammeter to measure the total current.
You could turn everything on, then full-field it and measure the voltage at the battery. Should be nearer to 18v than 14 at that point I think.
But best to read the book before jumping into something based on hearsay!

Anyway your alternator's wiring could not be more simple. If it's a GM based 1-wire setup you only need to connect a large gauge wire from the alternator's output post to the battery positive. For conveniences this is usually at the starter relay where the batter cable attaches.
If you do indeed have a Ford 3G with a "1-wire" self-exciting regulator, you still need to connect the big cable to the battery, but need also to connect the Yellow wire to the same terminal on the alternator as the battery cable, if it was not done for you already.
That's actually how we get away with calling ours a "1-wire" because the Yellow wire is already done for you before we ship it, and all you need to do is connect one wire to the vehicle.

But either way you need only to connect a sufficiently sized cable to the battery and run with it.
The original Black wire to the starter relay stays in place, but the original Black wire from the back of the alternator does get removed and capped off like it sounds like you've already done.

An important thing you need to consider though is whether or not your alternator is bolted to clean metal on the engine with clean bolts and clean threads. If it's not, you'll need to add an additional wire to act as a ground connection.
I don't think they need to be the same size as the charge cable, but I've always done that anyway. If not exactly the same, I've still used at least a 6ga cable from the case of the alternator to the engine or frame or body.

If yours is already well grounded, and you know for a fact(!) that your charge cable is good, clean and tight, then we're back to the fact that you have a bum alternator. Period.
As said, it can be new and still bad. But I can't think of anything on the vehicle side of things that can cause a low-charge condition other than those things already mentioned.

Good luck.

Paul
 
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MonsterBIlly

MonsterBIlly

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Dec 17, 2015
Messages
456
Paul,
Thank you.
I am going to add an additional ground cable from the Alt to the battery ground. It currently has a 4g wire and seems to be grounded well but the new ground will gaurdntee it it to be.

Yhe Alt is a brand new 100 amp powermaster. I had the same issue with the previous alt so i am thinking it is a wiring issue.
As stated, at idle it puts out 13.9v on the Fitech gauge. but when cruising on the highway it will start to deminish voltage until getti g into the low 11s or high 10s of voltage. If i stop and ket it return to idle it will start charging back up into the 1es rather quickly
 

DirtDonk

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Hmmm, now that is interesting for sure.
With two alternators doing the same thing (same type, or new vs original?) it sure sounds like their environment rather than the units themselves. But I sure can't figure what it could be.
Unless it's the main charging cable itself? Have seen new ones of those fail too, but never seen a new one fail like this. Where heat increases it's resistance. Really old ones, yes. But never a new one to this extent.

But hey! You never know what new crap you're going to run into with these things! Stuff that nobody's ever seen before!

By the way, got some pics of under the hood? Be interested to see what you got going on under there in case something else comes to mind after seeing it.

Paul
 

Steve83

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Yes, it very well could be a ground problem between the alternator case, that gold spacer, the painted block, and the oddly-positioned block ground cable. The thing that passes the most current is the starter, so the block ground should be on it. On the clean, UNpainted metal of the starter housing. The starter bolts should ground the rest of the block, but everything that relies on block ground (FITech, alternator, choke heater, etc.) needs a clean, tight connection to the block. Paint is an insulator - not a conductor - so remove it as this pic shows:


https://www.supermotors.net/registry/media/1055206 (for phone apps)

If you don't want to clean off the block paint, you can run additional ground wires across the block to each item that needs grounding, OR directly to the battery. But the cables shouldn't be bolted to the battery terminal - they should all be soldered into it, as this photo album shows:


https://www.supermotors.net/registry/2742/69178-4

Not that it matters for this issue, but: what you're calling the "solenoid" is actually the "starter relay". And what you called the chassis ground is actually the body ground (assuming it's against clean metal - if not, it's not grounding anything). A chassis ground would be on the frame, and it would serve the fuel level senders, a trailer, & a winch.
 
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