65 Dart Alternator Not Charging

[Austin Spencer]

I've recently bought a 65 Dart GT Convertible, and going through the list of issues it had and fixing them, and I'm up on the charging system since when I first got it, it wasn't charging. I checked voltages at the alternator and battery and figured it wasn't putting anything out, so I bought a new alternator and I've got the same issue.

I've read about the differences with the single field alternator and voltage regulator with one wire going to the field, and also the dual field with the newer voltage regulator. I've now got both styles of alternator, one with 2 field tabs that are both non-grounded, and one with a field tab and a grounded tab. My Dart has the older mechanical style voltage regulator, one dark blue wire going in from the ballast resistor, and one dark green going out to the field tab. My older alternator was the correct style for that voltage regulator, and wasn't working, so I swapped the new one on, did some reading, and read that you can ground one of the field terminals on the newer style alternators to get it to work. I didn't want that as a permanent fix but decided to try to test it, and I also got nothing.

From my limited understanding, the voltage regulator essentially sends out pulses that average to around 14v, depending on what the system needs, and so based on what the field wire has it changes what the alternator puts out. Is there a way to check if my voltage regulator is bad? I've got 12v switched power at the blue line from the ballast, but with the key in run, whether the engine was running or not, I had no voltage at the green wire, so I'd suspect it was the voltage regulator not putting anything to the field wire.

I've also noticed on many of the voltage regulators online to buy, they have 2 rods on the underside, and the one that came on this car when I bought it does not have those. Just curious as to what those are.

Since I have both styles of alternator now, would it be better to swap to the newer 2 field wire voltage regulator? Or should I get the same older style VR and stick with that?

 

[cudamark]

The simplest way would be to get a solid state replacement regulator for the early style alternator. No mods needed for that setup. I'd do a proper test procedure first to determine if it's a regulator problem or not. Make sure all the wire connections are clean and tight too.

 

[Austin Spencer]

I thought that the solid state had two wires coming out? Would I just connect the green and leave the blue disconnected?

I did a check to see if I had 12v at the blue wire of the VR, and checked for grounding and both were good. Are there any other ways to check the VR?

Edit: nevermind, just took a look at the wiring diagram for a solid state. That may be what I end up doing.

 

[Dana67Dart]

I've also noticed on many of the voltage regulators online to buy, they have 2 rods on the underside, and the one that came on this car when I bought it does not have those. Just curious as to what those are

They are resisters for the electro mechanical VR.

the ones without the resisters are typically fully electronic. But they do not function the same as the modern electronic with the v shaped connector.

You can temporally provide 12v to the single field terminal alternators field terminal.

That will "full field" the alternator and provide 16-18 volts to the system.

SO ONLY DO THIS FOR A FEW SECONDS.
be sure everything that can be turned off off is turned off.

This proves the alt works.

Then if you are not getting any voltage from the output of the voltage regulator that would indicate the VR is bad. The older electromechanical ones have a couple wires inside that act like fuses if the output is shorted.

Speaking of shorted... with the wire removed from the alt field terminal and from the VR, check that the wire is not grounded in any way.

 

[Murray]

While reading the voltage, use jump wire to connect both terminals of regulator, bypassing it momentarily. Does output jump up?

 

[Austin Spencer]

I tried that previously, bypassing the regulator by touching those wires together, and I didn't see the voltage jump. I do believe this is because I had taken off the ground, and was working with the newer dual field alternator. I'll retry this test with that ground and see what I get.

 

[Dana67Dart]

I tried that previously, bypassing the regulator by touching those wires together, and I didn't see the voltage jump. I do believe this is because I had taken off the ground, and was working with the newer dual field alternator. I'll retry this test with that ground and see what I get.

I feel like you have a good grasp of the difference and the workings of the 2 alternators.

the biggest difference in the VRs is the older 1 field wire provides a variable positive voltage to the field terminal and the newer 2 field wire VR (yes I know the VR does not have 2 field wires) it provides a variable ground to the alternator.

 

[Austin Spencer]

They are resisters for the electro mechanical VR.

the ones without the resisters are typically fully electronic. But they do not function the same as the modern electronic with the v shaped connector.

You can temporally provide 12v to the single field terminal alternators field terminal.

That will "full field" the alternator and provide 16-18 volts to the system.

SO ONLY DO THIS FOR A FEW SECONDS.
be sure everything that can be turned off off is turned off.

This proves the alt works.

Then if you are not getting any voltage from the output of the voltage regulator that would indicate the VR is bad. The older electromechanical ones have a couple wires inside that act like fuses if the output is shorted.

Speaking of shorted... with the wire removed from the alt field terminal and from the VR, check that the wire is not grounded in any way.

I did your method of temporarily providing 12v to the field terminal, on both the dual field and single field. For the dual field, I would get a very brief jump from 12.2v to 12.5, then back down. For the single field terminal alt, it would jump from 12.2 to 12.45 and then if I held it for a second or two it would begin to climb up, not very quickly, and got up to about 12.55.

I also checked with the wire removed from the alt field terminal and the VR if there was a ground, but there was not, so it is isolated.

I've currently seen the most promise with my older single field alternator, since it jumped up and then began to climb when I applied 12v to the field terminal, so I may look into returning this dual field alternator, and then getting a solid state VR, since it was mentioned above that I can use the single field alternator with the solid state VR.

If I am to go with the older alternator and solid state VR, I would just need to get that triangular plug with it, and hook it up the same, right? Blue to dark blue going to the ballast, green to dark green going to the field?

 

[67Dart273]

I did your method of temporarily providing 12v to the field terminal, on both the dual field and single field. For the dual field, I would get a very brief jump from 12.2v to 12.5, then back down. For the single field terminal alt, it would jump from 12.2 to 12.45 and then if I held it for a second or two it would begin to climb up, not very quickly, and got up to about 12.55.

I also checked with the wire removed from the alt field terminal and the VR if there was a ground, but there was not, so it is isolated.

I've currently seen the most promise with my older single field alternator, since it jumped up and then began to climb when I applied 12v to the field terminal, so I may look into returning this dual field alternator, and then getting a solid state VR, since it was mentioned above that I can use the single field alternator with the solid state VR.

If I am to go with the older alternator and solid state VR, I would just need to get that triangular plug with it, and hook it up the same, right? Blue to dark blue going to the ballast, green to dark green going to the field?

You need to add one wire for the 70/ and later system. Hook the new "flat" VR up like the old one, make sure it's grounded.

Hook the green to either of the two fields on the isolated field alternator, then the remaining field, you run a new wire up and around and tap it in to the blue, which is switched 12V run voltage from the key switch

 

[Austin Spencer]

You need to add one wire for the 70/ and later system. Hook the new "flat" VR up like the old one, make sure it's grounded.

Hook the green to either of the two fields on the isolated field alternator, then the remaining field, you run a new wire up and around and tap it in to the blue, which is switched 12V run voltage from the key switch

That would be if I kept the newer alternator correct?

Earlier in the thread it was mentioned that I could get a solid state replacement for the earlier alternator. I may be mistaken, are there solid state versions of the older style VR? If so I misunderstood, I could look for one of those solid state older style VR.

Edit: I found a solid state older style voltage regulator here: 100% New 12V Alternator Voltage Regulator FOR Chrysler Dodge Plymouth | eBay

I wasn't able to find a solid state one on summit or other usual sites. This one isn't too much, so I may grab it and see if it'll work.

 

[67Dart273]

HOW THESE WORK

Simply. Without getting into circuit complications, the output circuit of the alternator is the big stud and the case which is ground. That is ALWAYS hooked DIRECTLY to the battery (through the ammeter

FIELD. On the old units, up through 69, the VR FEEDS POWER TO the field, with the other field terminal grounded. This means that to get the alternator (if good) to charge "full" output, you jumper known good battery power to the field terminal after disconnecting the green

BEAR IN MIND you may have a poor connection / high resistance / open in the charge path from the alternator stud to the battery. CHECK VOLTAGE when running with "full field" both at the battery AND AT the output stud of the alternator if you are not getting substantial voltage output. THEN check RIGHT AT the field terminal to be sure your jumper is actually providing 12V TO the FIELD

The ONLY DIFFERENCE on the 70/ and later VR is that in effect the VR controls the "grounding" of the field to control output. One field terminal has 12V connected, and the VR controls the current through the field via the green, which is the ground side of the circuit.

This is comparable to your dome light circuit. The dome light(s) are INSULATED (isolated) from ground just like the 70/ later field, and are fed 12V to one side. To activate the lamps, the door switches GROUND the switch lead to complete the circuit. The 70/ later VR is the same idea

BE SURE when "full field" testing, that you make certain the belt is tight, and an ear listening for possible belt slippage, glazed belt/ pulleys. Be sure to carefully bring up engine RPM. Usually you can HEAR the alternator high pitched whining, indicating it is working. If you are careful NOT TO SHORT the output stud or the 3x insulated diodes, you can "feel around" with a screwdriver when the thing is charging hard and feel magnetism acting on the screwdriver.

 

[67Dart273]

That would be if I kept the newer alternator correct?

Earlier in the thread it was mentioned that I could get a solid state replacement for the earlier alternator. I may be mistaken, are there solid state versions of the older style VR? If so I misunderstood, I could look for one of those solid state older style VR.

Edit: I found a solid state older style voltage regulator here: 100% New 12V Alternator Voltage Regulator FOR Chrysler Dodge Plymouth | eBay

I wasn't able to find a solid state one on summit or other usual sites. This one isn't too much, so I may grab it and see if it'll work.

MOST old style VRs you buy are going to be solid state. As mentioned earlier, LOOK at the bottom. If there is "nothing" there it is solid state internally. If there are two wirewound resistors on the bottom, it is an electro-mechanical style VR

Unless you are "restoration correct" the newer, 70/ later VR is superior, and the 73 ish and later "square back" isolated field units are superior to all the older "round back"

 

[67Dart273]

WHENEVER YOU GET ANY rebuilt Chrysler alternator, make CERTAIN to check that the field is not shorted (say, improper brushes set up) and that if it is isolated field, that one brush is not GROUNDED. Isolated field units should have INFINITY or OPEN to ground from both brush terminals.

 

[Austin Spencer]

Thank you for the detailed breakdown. With that info it seems it'd be easiest to work with my earlier single field alternator and get a solid state older style VR, such as the one I posted from Ebay. Hopefully that'll do it.

 

[Dana67Dart]

Just for clarity.


Old 1 wire VR.

It is for the 1 field wire alternator

Can work with a 2 field wire alternator if one field terminal on the alternator is grounded.


It is electro mechanical but... There is an electronic version of this type of VR.

https://www.classicindustries.com/p...GzUw7lr42oxxiLz9gsRoCOMEQAvD_BwE&gclsrc=aw.ds


Full electronic versions of the 1 wire VR
typically do not have the resisters underneath

New style VR with V shaped connector.

It is only electronic and NOT compatible with the 1 field wire alternator.

 

[Austin Spencer]

So I've got a new VR in there, wired it up, still not seeing any charging.

I've got 12.08v at the battery, 11.66v at the alternator, 10.38v at the ignition side of the VR, and I can't read anything substantial from the field side of the VR. My alternator gauge sits about 1 like below center.

I wanted to confirm a few things so I can test on my own.
First, the field terminal on my alternator is connected to ground, since that brush is grounded on the other end. That is correct?

Second, should I be able to measure any voltage from the field output terminal of my VR?

Third, providing 12v from the battery to the field terminal should spike my alternator output to 16-18v, right?

Lastly I was curious about my alternator field terminal. Here is a picture.

There's 2 terminals, just mounted on top of one another. One has a brush on the end, the other comes from the alternator. This is different than most photos I've seen, and was wondering what this setup means.

 

[67Dart273]

I thought you were using the 70/ later "flat" regulator?

I cannot see enough of your alternator. It does not look right but I can not tell

 

[Austin Spencer]

No I've got the older style Alternator, and went with a solid state version of the old VR.

 

[67Dart273]

OI

If you are running the old style, 69/ earlier VR, you must have one brush grounded. To test the alternator, jumper 12V to the insulated field terminal, and bringing up RPM while monitoring battery V, V should climb and keep on going. Slow it down or stop if it gets above 16V

If not, transfer meter to alternator output stud and measure there. If the voltage stays low, below 12. something at battery, it's not charging

If it DOES charge, be sure the field wire from the alternator to the VR is good, be absolutely sure the VR is grounded, and that it is actually getting 12V from the system when running.

If all those are true, bad VR

Might be time to do a field current test, field might be shorted/ partially shorted. Read the book, if it's not in that old book, download the 72 Plymouth service manual from MyMopar.com. Section 8

 

[Austin Spencer]

Looks like I won't be testing anything tonight, the brush on the outside just fell apart. It was looking pretty fragile, guess it got bumped and the whole part is gone now.

The exposed one popped off.

I have the single field terminal alternator, but it had both of these brushes on it. I'm confused about the function of the one that was outside the alternator. The above picture is the way the terminals were mounted in the alternator. Is the exterior one just a spare?

Since this is the single field terminal, there isn't an "insulated" one, since this is ultimately connected to the ground terminal which is grounded to the case, correct?

 

[67Dart273]

I don't know without seeing it. Never seen a "spare."

 

[Austin Spencer]

It's in the above photo, there's one terminal bracket with a brush that is inside the plastic insulator, and one that is mounted outside with the brush exposed. I'm assuming now that was just a spare since it would be doing nothing.

This is my field terminal insulator without the "spare".

Now that I've taken it apart I'm better understanding it. I will run those tests mentioned above and see what comes of it.

 

[67Dart273]

Check with your meter, and use the low ohms scale, stab the probes hard. One brush should be grounded, the other brush to the case should be an ohm or 2 or 3

 

[Austin Spencer]

Check with your meter, and use the low ohms scale, stab the probes hard. One brush should be grounded, the other brush to the case should be an ohm or 2 or 3

Just checked, I've got 6 ohms

 

[67Dart273]

That sounds OK. Not sure what is going on. As I said above, I would jumper power into the field and see if it charges, then reconnect the VR and see.