Alternator passed test. Original VR overcharges the battery. 4 different VR’s no charge at all. I can jump the VR wire harness and it works. What am I missing? And where does the stator wire White/Gray run, ignition? It’s not to the VR.

 

Where was it tested? Parts store?
Have you tested the wires going into the VR and inspected all the wires going to and from the alternator and voltage regulator?
Unfortunately, it's not uncommon to get three, four, or even five bad parts in a row, right out of the box.
Were they all the same brand, from the same store? Try a different brand.
If they were chosen for price and warranty, it's even more likely. If so, get the more expensive ones and see if that helps.
When it comes right down to it though, if you have a junkyard nearby, you might be better off finding a crusty old used one that still works.
Which wires are you jumping, exactly? And what exactly do you mean when you say it works?
When it's working, are you measuring voltage at the battery? If so is it approx. 14.5v or so, or is it still overcharging in the neighborhood of 18v or so?
Is this an ammeter truck, or a battery charge lamp truck? Have you tested the wires going into the voltage regulator? And are their four colors, or three? Sounds like three, but wanted to make sure.
Should be White w/black, but the black has probably faded.
The fact that you say it does not go to the regulator says that your truck is equipped with an ammeter. That correct?
If so, it's only function on our trucks (what year is yours by the way?) is to power the electric choke on the carburetor.
If you had a battery charge indicator lamp on the dash, it would be running to the VR's "S" terminal before splitting to the choke as well.

Wire functions to test (if ammeter equipped):
1. "I" post. Blank.
2. "A" post. Yellow wire (or Yellow w/white) should have battery voltage at all times.
3. "S" post. Green w/red stripe wire, should have pretty close to battery voltage only with the key in the ON position. Not in ACC though.
4. "F" post. Orange wire that runs directly to the "FLD" terminal on the back of the alternator.
5. Tiny Black wire to one of the attaching screws holding the regulator to the body. Check to make sure it's not broken.
6. Could be a second Yellow wire in the same cavity as the other Yellow "A" wire, which runs to a radio noise suppression capacitor.

Alternator should have just these wires:
Large gauge (probably 10g or so) Black wire directly to the battery side of the starter relay.
Small White w/black stator wire to the choke.
Orange FLD wire to the regulator.
If the harness is original, there should be a metal ring molded into the black strain relief assembly that is bolted to one of the case screws. There is one marked "GRD" for ground, but it's not always the one that Ford used.
This ring is attached to the small Black wire that runs up to the regulator attaching screw. This maintains the same ground potential between the regulator and alternator.

Another thing to just double check, would be that the alternator case is well grounded to the engine. This is done through the case attaching points of course, but if the engine block has been freshly painted, or is heavily rusted and the bolt and hole are rusty too, is no longer a very good ground.
If any of those things are present, clean off the mating surfaces and make sure the alternator is well grounded to the engine.

That's all I've got for now. It's late/early and I'm not thinking clearly.
Let us know more about things. Did this just start out of the blue, or has it been having charging issues for awhile? Truck is new to you, or you've had it for awhile.
Stuff like that.

Paul

 

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Not sure how to use this quote. So pay no attention to that last response.

 

Hey Jpug
I think what 1 Ton is trying to say is he needs more info concerning your truck.
Year, gauge or lights, and the explanation of what you are working on....
He has provided you with great questions to answer to solve your issue JUST NEEDS THE ANSWERS to his questions...

 

No problem. It’s a lot of work to use the quote function, but it works really well when you’re trying to separate things.
I did see your answers to the first couple of questions, so I would be looking at other things now that you’ve tried multiple regulators from multiple sources.
It’s still possible to get that many bad ones, but what you did reduces that possibility by quite a bit.

One of the thing to remember. When you’re disconnecting and connecting the new regulator, make sure that they are well grounded first. Never connect the regulator while it’s just hanging there or not bolted to the body in a clean manner.
Doing so con fry even a brand new regulator.

 

First let me say, Thank you!

So we bought this 1976 F100 2 yrs ago. Only electrical I added was a fan relay back when we first got it. It already had an aftermarket radio in it.

This all started a 2 weeks ago when my son said he heard a pop behind the dash and the radio apparently started acting funny. Couldn’t find anything wrong. Now I don’t remember if it was that night or a few days later the battery was dead. I checked grounds pulled fuses but still get a 2.1 amps draw. The only way I got it to stop was either pull FLD plug from ALT or pull harness off of VR. Bought Reman ALT and new VR and still had draw. Swapped ALT and still had draw but also was getting the 17-18 volts when engine running. So multiple VR’s later still overcharging and still draw. In the process of this the radio has fried and so did the fan relay. So I bought a new ignition switch. Was told a bad switch could cause an overload. And thought that might just be my issue with it all. I haven’t put the fuse back in to the ACC port which the radio the fan relay and the wipers were plugged into. Just found that out when tracing wires. Figured that was too much, but it has been working that way for the last year or so. Just trying to figure out the charging issue fist. So that’s where it stands.

Thinking of just buying new harness!

[QUOTE=1TonBasecamp;21547970] Tested at AutoZone. I have tested the wires a few times on both. For continuity at least. I guess I haven’t checked the w/blk inside the cab. I assume it’s to the back of the cluster.?

I tried multiple Carquest VR. 2 Duralast and 1 Echlin from Napa which was the higher quality. All these have no effect. The original one is allowing the Volts to get to 17-18 volts.

And what exactly do you mean when you say it works?
So I jump the F and A from the VR harness and it runs up to 17 - 18 volts on the batttery terminals. It has 6 wires because I bought a new harness. Not sure the ammeter works on the cluster. It’s always in the middle. It has aftermarket meters.




The choke is on its own wire plugged into the end of a harness with a blade. I learned I can wire that into the new VR harness.

I will do this test.

The ALT does have 3 wires like you say. No metal ring in strain relief. It’s a 10g wire maybe 14g attached with the engine ground. How it was when we bought. The ALT harness has been remade but they all checked out.

 

might make sure your voltage regulator is a 12v not a 6v and not a 24v just to be safe. a mis boxed batch of regulators can cause big confusion.

 

I haven’t figured out how to do the quote thing from my phone yet, so just going to wing it with a couple of answers.

So we bought this 1976 F100 2 yrs ago. Only electrical I added was a fan relay back when we first got it. It already had an aftermarket radio in it.

Why a fan relay? What fan is installed? Electric fan only, or a combination?

This all started a 2 weeks ago when my son said he heard a pop behind the dash and the radio apparently started acting funny.

No smoke?

Now I don’t remember if it was that night or a few days later the battery was dead.

A quickly dead battery is usually the alternator. Either because the regulator is energized, or because the diode in the rectifier are dying and letting current pass the wrong way.
with only 2.1 A being drawn, that doesn’t sound like a wacky alternator.

I checked grounds pulled fuses but still get a 2.1 amps draw. The only way I got it to stop was either pull FLD plug from ALT or pull harness off of VR.

pretty much says that you’re on the right track at least. We just have to figure out why.

Bought Reman ALT and new VR and still had draw. Swapped ALT and still had draw but also was getting the 17-18 volts when engine running.

you say “but also” in the same sentence. Does that mean that it wasn’t overcharging before? I thought that was also what started this quest. Did the overcharging only happen after you started replacing things?

So multiple VR’s later still overcharging and still draw.

When you tested the wires at the voltage regulator, was there any power on the green w/red wire when the key is in the OFF position? We don’t care about continuity at this point. Just voltage.

In the process of this the radio has fried and so did the fan relay.

interesting. Are you sure the radio wasn’t fried when you heard the pop? And when exactly did the fan relay fry?
and where exactly is the fan relay getting power?
One terminal is getting power directly from the battery? And one from the ignition switch?

So I bought a new ignition switch. Was told a bad switch could cause an overload.

I don’t see how. Then again I don’t know everything about electricity either. An ignition switch only passes through as much occurred as as necessary as demanded by the accessory. Only a short circuit could fry something else, and if you had a short circuit in the ignition switch, you’d have a lot of other problems!
Including usually letting smoke out!

And thought that might just be my issue with it all. I haven’t put the fuse back in to the ACC port which the radio the fan relay and the wipers were plugged into.

Why are your wipers running off of the same circuit? Hopefully that’s just the switching circuit for the relay because if not, that’s too much power being pulled through the ignition switch.
your wipers should have their own fuse in the factory fuse panel.
Or are you talking about the factory fuse box?

Just found that out when tracing wires. Figured that was too much, but it has been working that way for the last year or so.

Maybe it just wore out the switch ahead of time. Might not be your issue, but it’s still possible
Unfortunately, it’s also possible. The ignition switch is bad right out of the new box. You might need to test a few things.
but as long as it seems to be working correctly, we will cross our fingers and hope for the best. :-)

Thinking of just buying new harness!

well, that’s one way to cure something. Or add more headaches!
The new ones are great. But it’s not for the faint of heart and not just a one day affair. If you’ve done Wiring before though, it might just be the answer.
but I’ve never run into a charging circuit issue yet, that needed a new wiring harness to fix it.
If you’re still dealing with bad parts, a new harness isn’t going to fix that.

I have tested the wires a few times on both. For continuity at least.

As mentioned previously, check voltage.

I guess I haven’t checked the w/blk inside the cab. I assume it’s to the back of the cluster.?

not that I’ve ever seen. If you’re talking about the state or wire, it has no business being in the cab that I’m aware of. I’ll have to review a diagram of a 76, but it’s only function should be as I previously stated. It powers, the choke.
If you have a wire there already of a different color, we need to know what it is.
Maybe it’s all aftermarket. What kind of carburetor is on the vehicle?
In fact, now it’s about the time we ask for lots of pictures.

I tried multiple Carquest VR. 2 Duralast and 1 Echlin from Napa which was the higher quality. All these have no effect. The original one is allowing the Volts to get to 17-18 volts.

What are all the rest doing? Same 17 to 18 V?

So I jump the F and A from the VR harness and it runs up to 17 - 18 volts on the batttery terminals.

so it passes the “full fielding” test as expected. We already know the Alternator can put out more than as needed, because that’s how it’s testing every time you try it.
I’m afraid that it might end up being something really simple that we’re overlooking.

It has 6 wires because I bought a new harness.

what are the six wires and where are they? What is the harness? Where from and what part number and what year and model are they for? Got pictures or a link to the description?

Not sure the ammeter works on the cluster. It’s always in the middle. It has aftermarket meters.

They almost never work. The Early Broncos got a different ammeter that worked 95% of the time in 95% of the Broncos. The full-size trucks got a shunted type, that worked less than 10% of the time and in only 10% of the trucks!
it was a really crappy and unreliable design. Other companies could make them work it seems, and we can often make them work if we fiddle around enough. But it was almost never worth the trouble.
What kind of meters does yours have from the aftermarket? And is it a voltmeter, or an ammeter?
If it’s an ammeter, it could also be the cause of your troubles.
Again, pictures would help.

And while we’re on the subject of ammeters, is this a stock 50 to 65 amp alternator? Or something different?

The choke is on its own wire plugged into the end of a harness with a blade.

Need to see pictures of that, please.

I learned I can wire that into the new VR harness.

Sorry, but I don’t think so. That doesn’t sound like a good idea at all.
Why isn’t the voltage regulator running off of its existing factory wires?

The ALT does have 3 wires like you say. No metal ring in strain relief. It’s a 10g wire maybe 14g attached with the engine ground. How it was when we bought. The ALT harness has been remade but they all checked out.

Remade, as in bought? Or remade as in rewired by you or the PO?
Without that metal ring, you will need to add a ground wire directly between the case of the alternator and the voltage regulator. Don’t rely on the engine ground alone. Make sure that the regulator is grounded directly to the alternator.
And do that before you plug in power to the next new one.

 

I will take pics and get backed to you.

This is my fault but left out an IMPORTANT detail. The engine is a 83 Mustang 5.0. But most parts interchange. It’s a bare bones setup. Done very sloppy by all the previous owners. There are unused harnesses. And stuff just wired to make it work, like the choke.

I did find out today that the battery is bigger than required. It’s a 65 class.

 

Bigger batteries are better at least in a Bronco… :-)
OK, at least up to a point.

Which alternator is it running? Is it the serpentine accessory drive that came with the Mustang engine? Or is it the old truck stuff with v-belts?
this could be another critical factor and how things work.

 

60 amp and accessory belt.

 

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This is the wht/blk stator wire. It runs into the harness as shown. The end plugs into the other half that connects to the back of the alternator.

 

First of all, WHAT A CLUSTER! Wow, someone was really trying to get "creative" with all the wiring, re-wiring, mis-wiring, and un-wiring that I can see just from the pictures.
Typical PO (previous owner) stuff though. Everybody used to think they were wiring experts, and just throw stuff all over the place. From here so far, there does not look to be any rhyme or reason to their mods.

Otherwise, sorry it took so long to reply. Had to get to the computer and do a lot of copying-and-pasting to get this all to work.
It's a bit different than normal, because your quotes were all within my quotes, which means that the site can't differentiate. Therefore no "quote" function after the fact.
Anyway, onward!

Right you are.
Was this with the relay, or did you put the relay in during all of this fact-finding odyssey?

Can't remember every seeing a Ford with a "non-serpentine" wide ribbed belt accessory drive before. Wonder if it's also modified, or if that's how Ford did it.
The first serpentine drive system I'd ever seen was a '79 Mustang with a V6.

Was the pop still from under the dash? What about the smoke itself? Under the dash, or under the hood?

And you know it got fried, how?

Can you post a pic of the relay and the wire directly?
And can you tell just how the relay was wired at all four points?

Well ain't that interesting... The Yellow connector with the Orange wire might be for intermittent wiper power. I did not think that the wipers used that 3-wire connector, but that would explain it.
The other two don't look like they belong there. And certainly NOT the stator wire from the alternator!
The stator terminal on the back of the alternator puts out a lower voltage when the alternator is charging. Something in the neighborhood of 9v or so. So there is no logical reason for that to be connected to a 12v switched circuit.
Perhaps the PO had connected it to the old Green w/red wire of the regulator? Do you still have a Green w/red wire coming out to the regulator?
That Yellow receptacle/connector is a common item for just about all truck wiring harnesses. But it's often not utilized. And I have only rarely seen all three positions utilized from the factory.

Well, it's still possible that you've received a rash/ration of defective new parts. But just as likely is your wiring is still buggered. Maybe it worked for a time, and something got jostled while you were working on it.
Don't know yet, but will soon.

This is typical of the Chinese interpretation of Ford's whacko wiring methodology. And the fact that they did not utilize the same thing on all vehicles, but instead made it different at least for two styles, but then probably a third style for the '74 and earlier trucks. It has confused more people than it has helped, but making the connectors wrong, with sometimes the wrong color, just makes it that much worse.
Your particular truck had just the alternator and the regulator. Correct? Earlier models had some kind of extra module in-between the two.
And just to be sure, you did say yours has an ammeter in the dash. Correct?
Either way, no matter what, the following two scenarios are how yours should be connected. No matter what the wire colors are!

(With Ammeter)
1. F location - Black in your case, Orange originally - Runs straight to the FLD terminal of the alternator.
2. S location - White in your case. Green w/red originally - Ignition switch hot in the ON position only.
3. A location - Yellow(ish) in your case. Yellow originally - Full battery voltage at all times.
(stator is either not connected, or ONLY connected to the choke on the carb. It has no other reasonable function unless you tell us otherwise.

(With BAT/CHG Lamp)
1. F location - Black to the FLD terminal on the alternator.
2. S location - White Stator wire to the STA terminal on the alternator.
3. A location - Yellow to battery 12v spliced somewhere inside the harness tape.
4. I location - Green to ignition switch powered up when ON only.

So look at those two scenarios carefully and make sure that yours matches your gauge cluster.
Don't hook wires up to anywhere they were not originally intended, unless there are problems with your existing harness.
In which case... The new harness is sounding better and better.

Good luck.

​​​​​​​Paul