You have not checked the output of the alternator on the vehicle?

You should have 13-14V output from the alternator, which you can measure at the output from the BAT terminal on the alternator. It is usually the large one on the back with the large wire (should be red) that then goes from the BAT terminal to the solenoid and carries that voltage.

Just before the solenoid on that wire should be a fusible link, if it is burnt out you will not find the same voltage at the solenoid. Before you do anything else check the voltage at the BATT and the solenoid.


If you do not have voltage at the BATT it may be because the FIELD or FLD terminal is not being energised. That is the job of the regulator.

The external regulator, you may find it has three wires, a black, a yellow and a green, is wired as follows:

- The black is switched from the ignition and tells the regulator to start producing. You should have battery voltage on this in Run. No power, no run.

- The yellow wire is a voltage sensing wire. It senses the volts near the solenoid and keep alternator output a bit higher. You should have battery voltage on this one at all times.

- The last one is a green wire to the alternator Field or FLD terminal. Without energisation of the field coils you will not get power out. It will be slightly higher than battery voltage and be energised when the black wire has voltage.

When you have that all tested it may show you the fault is in the wiring. A blown fusible link is common but so are wires dropping off terminals.

 

I am using a multimeter to check all of these systems. I get the same voltage directly on the battery as I do off the hotwire on the alternator to ground. This jeep was completely rewired a few years ago, and it was done very well. I would love for it to be a wiring issues but I seem to get the same values if I go "around" the wiring with alligator clips. The alternator should work with the regulator unplugged because when they checked it at autozone they only hooked up the hot, and a ground.

 

Basically anywhere I check the voltage, battery, alternator, solenoid, i get the exact same value.

 

I am thinking about getting the single wire version from Autozone. It would take 2-3 days to get the 3 wire style. I should be able to just rewired the harness and delete the external regulator.

 

sounds like the regulator seeing as autozone is testing your by using there built in regulator and its testing good. not sure if you can bypass your regulator to see if it will work but the fact that it works on autozones machine tells you something, that its good. im running a one wire but thats because i use to have a old generator, really low amp output, check out ebay, should be able to find a new one for under $50.00, 100 amp.

 

At autozone they clamped a ground to the body of the alternator, and then hooked up a hot wire. You think a regulator is built into that hot wire? They did not hook up anything to the regulator post on the alternator. Does anyone know if the regulator is required to "turn on" the alternator, or does it just regulate the output that's already coming out?

 

Found this in another forum: "do a google search on how to full field that alt. They will tell you which wire to either full ground or full power to full field the alt. Usually its a wire you ground. The alt outputs usually 14.5 volts when charging. All the regulator does is adjust the field coils of the alt so it charges a lot or a little.

so the first test is to full field the alt and see if it will charge, if it will the regulator is bad."

 

What's All This Fuss About One-Wire Alternators?The Powermaster people tell us that the most asked tech question is: "How do I hook up a one-wire alternator?" One-wire alternators are becoming increasingly popular in modified cars as well as typical street cars due to their simplicity. The only wire that needs to be connected is a cable from the large output terminal on the alternator to the battery. One-wire alternators begin charging using a circuit that senses internal voltage once the alternator is spinning fast enough. This is why one-wire alternators require the engine to be revved past roughly 1,500 rpm to begin charging. Once energized, one-wire alternators will charge at idle no problem. Factory three-wire alternators use 12 volts from the ignition switch to energize the charging circuit, which is why these alternators begin charging the instant the engine is running. Most aftermarket one-wire alternators are designed so they can be used as either one-wire or three-wire installations.

Read more: http://www.carcraft.com/techarticle...charticles/ccrp_0806_muscle_car_electrical_tech_tips/viewall.html#ixzz2llpr2zZV

My alternator might not be getting that signal.

 

In summary.. the alternator does have to get a "turn on" signal from the regulator. That is probably my issue. I'll just upgrade to a 1 wire alternator anyways.

 

Bagus.. after a lot of reading your post makes perfect sense now.
Thanks

 

Finally got the 1 wire alternator installed. I had to narrow one of the ears on the alternator, and trim the fan blade fins for it to fit.

 

 

The PROBLEM with the one wire system was spelled out by you yourself; and that it doesn't charge at low RPMs. That's not good for off roading where the RPMs are low and the torque high.

It IS a clean set up for street rods, but I have outs about Jeeping with one.

 

They charge the same as the 3 wire systems at low RPM as soon as they "excite." If you jump the #2 pin to the hot post on the back, it will excite as soon as you start the engine. I have read multiple places that they put out just as many amps at low RPM. Where did you hear this?

 

Not exactly the way it works.
If you want to have some RELIABLE reading on the 'One Wire' try the 'Transpo' catalog specifications and applications section.
Since Transpo is about the largest supplier of rectifiers, regulators, ect. to the rebuild market in the US, they are pretty reliable about what they publish.

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The #2 pin on the voltage regulator is a 'Sense' or 'Sample' wire.
It give line voltage reference to the regulator, and it supplies current to the rotor via regulator.

The #1 terminal is the 'Excite' wire.

Excite is to kick off charging, and those SI units take an 'Excite' anytime the shaft speed drops below the 'Excite' point.

One wire alternators need to be 'Excited' once they are put on if they have been in storage very long.
They rely on residual magnetism in the rotor pole pieces to start charging, and if the unit has been on the shelf too long, or in a vehicle that hasn't run in a while, you will have to 'Excite' them to get them charging again.

One wire alternators don't charge very well at low RPM. If you are a lead foot, right pedal driver, or driving a CJ as a commuter, it will probably be OK, but if you are a low gear, idle driver, you will have issues keeping the battery charged.
One wire alternators were primarily designed for industrial placement engines, like light plants and air compressors that would run all day at fairly high RPM.
Some farm tractors use them, but unless the tractor is run frequently they wouldn't stay 'Polarized' and stop charging entirely.

You will also pay a price for One Wire connections besides the no charge conditions at low RPM and having to excite after the vehicle sits around a while, and that is reduced regulator life expectancy.
Since the regulator is 'Hot' all the time, the regulator won't live as long as one that is 'Excited' when needed, and not 'Hot' when it's not in use.

Not an idea situation, but better than the 'No Charge' condition you had before.

 

OK I think I know what you are saying. If you don't use the "sense" wire properly, you will get lower voltage at idle. This is explained very well here:

http://bob_skelly.home.comcast.net/~bob_skelly/alternator_conversion/wiring_alternator1.html

 

My alternator can be used as a 3 or 1 wire.
The problem with me earlier posts is that I was thinking that "1 wire alternator" meant the same thing as internally regulated.

When I was saying "convert to 1 wire alternator" I should have said "convert to internally regulated."

 

It would have helped to have mentioned what year it is and what alternator it had to convey that external to internal regulation thought process.

 

It's a 1975 that originally had an external regulator.

 

This site says the #1 is for the idiot light.

http://www.oldengine.org/unfaq/10si.htm

The 10SI has three terminals (including those with a 1 wire regulator).
The large "BATT" terminal which gets connected to your battery positive. (Or Terminal Post if your vehicle is so equipped).
And a dual terminal connector. (Repair pig-tails for this connector available at any autoparts store. Or, salvage with alternator if pulling the alternator from a vehicle).
The #1 Terminal. (Marked with a "1" on the case)
This terminal is used to connect to the dash warning light.
For the warning light, a lamp is wired in series with a switched voltage source. During normal operation the lamp stays off. If the regulator is damaged, the #1 terminal provides ground, and the warning lamp will light. Usually.
This terminal is also active on 1 wire regulator equipped 10SI alternators.
The #2 Terminal. (Marked with a "2" on the case)
This terminal is used to excite the 10SI into operation. (3-wire 10SI)
It is connected to the battery positive.
For simplicity you can connect the #2 connector pigtail directly to the "batt" terminal on the alternator.
The terminal is present on 1 wire regulators. Used only for those that require the stock connector to fit snugly.
If you are converting from a 3wire 10SI to a 1 wire regulator you can hook up all your stock connectors, and run it as is. However, thats wasted money unless you plan on cleaning out some wiring under your hood.

If the 1 wire is for cleaning out wires, you only need to retain the "BAT" wire. The #1 & #2 terminal wires can be eliminated. Don't be surprised to find that the #2 wire only goes a short way into the harness and spliced into the "BAT" wire.
The 1 wire regulator comes with a dust plug for the #1 & #2 terminals.

 

This site says the #1 is for the idiot light.

NOPE! You *CAN* run a failure light in place of the resistor or diode to #1, but it's not 'REQUIRED' and it's not what the #1 terminal is for.

#1 is the 'Excite' wire to kick off charging.

The 10SI has three terminals (including those with a 1 wire regulator).
The large "BATT" terminal which gets connected to your battery positive. (Or Terminal Post if your vehicle is so equipped).
And a dual terminal connector. (Repair pig-tails for this connector available at any autoparts store. Or, salvage with alternator if pulling the alternator from a vehicle).

It has the two terminals, but with one wire regulators, those terminals are connected just below the plug...
Since the 'Excite' is 'Grounded' when the alternator isn't charging, that would drain the battery through the 'Sense' or 'Sample' or #2 connection,
So internally, the #1 terminal does nothing in the regulator.

The #1 Terminal. (Marked with a "1" on the case)
This terminal is used to connect to the dash warning light.

It can be used for a 'Charge Failure' light, not necessarily what it's for.
This is the 'Excite' terminal to kick off charging at lower RPM when the alternator isn't producing enough internal current to power up the rotor.

Since the 'Idiot' light, or charge failure light is taking place of the normal Resistor wire,
And it's still switched 'Off' by the key switch to keep from running the battery down when engine isn't running,
It's handy for a few things, like the light, or you don't have to use it at all, and that makes the unit more like a 'One Wire'... You have to rev the engine up pretty high to start charging,
And it won't charge at lower RPM like 'One Wire' alternators do.
It also will have to be 'Excited' again when it sits on the shelf or in an unused vehicle very long.

For the warning light, a lamp is wired in series with a switched voltage source.
During normal operation the lamp stays off.
If the regulator is damaged, the #1 terminal provides ground, and the warning lamp will light.

That's pretty accurate 'Function' description.
When the alternator isn't charging, that terminal becomes a 'Ground' though the rotor slip rings.
The alternator is trying to make 'Charge' via the regulator, but doesn't have the internal voltage to do it, so it's trying to access voltage for the rotor from terminal #1 to 'Excite' charging.

Once charging starts in the alternator, that terminal becomes 'Positive' since the regulator has taken control of the rotor and no longer needs the 'Excite' voltage to try and kick things off.

The fact it switches from 'Negative' to 'Positive' baffles some people, but once you see the schematics of the regulator, it makes perfect sense.

If you take a good look at the schmatics of the regulator, the fact the #1 terminal switches to 'Positive' when the alternator starts charging internally is a fluke entirely.
That fluke is put to good use by installing an idiot light, since the excite is switches, turns off with the key switch, and since it turns 'Positive' once the alternator starts charging, it's perfect for an indicator light connection.

The lamp itself becomes the resistance to keep the positive from the alternator charging from backfeeding the ignition once the key switch is turned off... And that means you don't need a resistor wire anymore to do the job the lamp is doing.

Good deal all the way around! Not bad for a fluke of the early semiconductor regulators!

This terminal is also active on 1 wire regulator equipped 10SI alternators.

All SI alternators have an 'Excite' terminal (#1) unless they have a 'One Wire' regulator.
Even the really large heavy equipment alternators had provision for an Excite of some kind.

The #2 Terminal. (Marked with a "2" on the case)
This terminal is used to excite the 10SI into operation.

The #2 terminal has a thicker wire for a reason...
This terminal does two functions,
The first being supplying a LINE VOLTAGE SAMPLE to the regulator so the unit doesn't overcharge.
The second being a supply to the rotor (Via Regulator) so the unit can make more power than it's consuming.

Again, it's a quirk of the SI style regulator that the sample has to be taken externally...
The idea was, and Jeed didn't use, to take that sample at THE BATTERY, to sense DIRECTLY what the battery charge state was.

On larger units, with big batteries that were less sensitive then the little car batteries we use was to sample from the FARTHEST POINT on the harness,
AFTER ALL ELECTRICAL LOADS, and make enough voltage/amperage for EVERYTHING on the line...

Since Jeep used a VERY short run of wire from the battery to the 'Sample' point, they get a pretty fair reading of demand by just connecting to the 'Battery' or 'Line Voltage' at the back of the alternator.

It is connected to the battery positive.
For simplicity you can connect the #2 connector pigtail directly to the "batt" terminal on the alternator.

The terminal is present on 1 wire regulators. Used only for those that require the stock connector to fit snugly.

Most 'True' One Wire Regulators will come with a NON-Removable plug in the hole where the normal #1-#2 wire plug goes in. If you see a black or red plug in there, flush with the case, don't try to remove it!

If you are converting from a 3wire 10SI to a 1 wire regulator you can hook up all your stock connectors, and run it as is. However, thats wasted money unless you plan on cleaning out some wiring under your hood.

Probably shouldn't plug in the connector with a true 1 wire, some of they hybrids allow for the connector, but a true one wire will have that connector port plugged since you don't need the plug at all.

If the 1 wire is for cleaning out wires, you only need to retain the "BAT" wire.

True, but have the alternator 'Excited' on the bench before you take it for install, they will loose the ability to self excite with time on the shelf.
If you get it 'Excited' on the bench, then take it home, you know two things right away,
One is the unit WORKS and is charging,
Second being no matter how long it was on the shelf, it's excited and ready to run when you get it home.

The #1 & #2 terminal wires can be eliminated. Don't be surprised to find that the #2 wire only goes a short way into the harness and spliced into the "BAT" wire.
The 1 wire regulator comes with a dust plug for the #1 & #2 terminals.

Like anything this complex, it seems simple, and there are HUNDREDS of variations, about 300 different regulators for he smaller SI series...
But you are correct about cleaning up wiring in the engine bay.

My personal choice is for the excited version and if the vehicle didn't come with an 'Idiot Light', I install one and use it.
Since I RARELY look at gauges when I'm wheeling, I like to have a large, red 'LOOK AT ME' light get my attention when I pack the alternator full of mud and it stops working...

Now, if I wasn't so cheap, I'd install a SEALED alternator and not worry about the mud, but I'm a tight bastard with a dollar bill, and I burn the cheap ones instead of doing the 'Right' thing and getting a sealed unit!

 

In any case.. I'm running a 3 wire alternator not a 1 wire.