Alternator or VR issue?

[DH-66cuda]

So I have been trying to chase an issue with my battery not showing it is charging. When I test at the battery with the key off I am at 12.6, running around 12.3/12.4 never appears to be charging. Below is everything I have done and just looking for suggestions.

• Had Alt tested at local auto store and passed
• Had battery tested and pasted
• Tested Alt Stud with key off - gets same as battery 12.6
• Tested Alt stud while running getting 11.8ish
• I have removed the FLD line (Single line Alt) and grounded straight to the car firewall still getting 11.8ish at Alt Stud
• I have tested with key on Blue wire at voltage regulator and get voltage
• Replace voltage regulator... no change in issue
• Ran bypass wire from ALt Stud to battery positive no change
• Verified Fuse Link has continuity along with all other lines for Alt to VR

Is this a bad alternator even though tested ok at store?

Is there another test I should be doing to verify what is truly the problem?

Thanks Don

 

[67Dart273]

Well you tried, and you only, really, made one mistake

Instead of GROUNDING the alternator field terminal, you must jumper it to 12V. I would not use the alternator stud, because there can be an open in there that can lead you down "a path", ---the wrong one. "Rig" a wire direct either to battery pos. post or starter relay "big stud." If it charges, then it either has to be the VR, the green wire (which has happened!!) or the VR is not getting power under a load, meaning...........

CAVEAT........"Let's say" there is a poor connection where the blue IGN power wire is spliced. You might measure that with your meter DISconnected and it might show fine, but measuring it connected, the load from the field drawing current might "break" the bad connection.

 

[Dana67Dart]

I have removed the FLD line (Single line Alt) and grounded straight to the car firewall still getting 11.8ish at Alt Stud

Are you saying you have a pre electronic voltage regulator

and your alternator only has the heavy power feed to the car and the green field wire.

Or

 

[DH-66cuda]

Yep pre electronic and single field wire

 

[Dana67Dart]

Then yes to see if the alternator is working you want to jumper 12v to the field terminal on the alternator but it will go to full charge and high voltage. Have everything set up ahead of time. To measure voltage at the battery.

If it doesn't go to like 18v the alternator is not functioning correctly.



When you said you grounded the green field wire, did you do it at the VR with the wire removed.

If not you probably blew out the VR.

There is actually 2 fuseable wires inside to prevent a wiring melt down if the green field wire shorts etc.

One last thing, is your alternator a round back or a square back?

 

[66signet]

I'm watching this, I am having the same problem.

 

[67Dart273]

Yep pre electronic and single field wire

Read post 2

 

[DH-66cuda]

Then yes to see if the alternator is working you want to jumper 12v to the field terminal on the alternator but it will go to full charge and high voltage. Have everything set up ahead of time. To measure voltage at the battery.

If it doesn't go to like 18v the alternator is not functioning correctly.



When you said you grounded the green field wire, did you do it at the VR with the wire removed.

If not you probably blew out the VR.

There is actually 2 fuseable wires inside to prevent a wiring melt down if the green field wire shorts etc.

View attachment 1716101392


One last thing, is your alternator a round back or a square back?

Round back... will give the jumper a try tonight after work.. will reply back with results.. thanks everyone for the suggestions

 

[Mattax]

Is this a bad alternator even though tested ok at store?

if you go again, get a copy of the test print out.
Without that we don't know what the test(s) consisted of, so can't jusdge the results.

I have removed the FLD line (Single line Alt) and grounded straight to the car firewall still getting 11.8ish at Alt Stud

See Dana's comment about the fuses in the regulator.
(you can remove cover and check those on a mechanical regualtor)
Also, to better understand why that blew the fuses, look at the sticky titled Identifying Chrysler Alternators.

Replace voltage regulator... no change in issue

That should eliminate the likely blown fuse in the VR.

• Tested Alt stud while running getting 11.8ish
• I have removed the FLD line (Single line Alt) and grounded straight to the car firewall still getting 11.8ish at Alt Stud

IF this was tested at same time as when the battery positive was 12.3 Volts, this suggests a signficant amount of resistance between the battery positive and the mainsplice, or poor grounding.

I have tested with key on Blue wire at voltage regulator and get voltage

The voltage at that terminal should be very close to the same as the supply voltage.
IF these measurements are all done at the same time, same conditions (engine running, alternator not working), this is a useful diagnostic.

 

[Mattax]

IF this was tested at same time as when the battery positive was 12.3 Volts, this suggests a signficant amount of resistance between the battery positive and the mainsplice, or poor grounding.

Diagram this.
Typically the ignition will draw a couple amps, and the rotor will draw a couple amps. The ammeter's needle will indicate roughly 5 amps discharge.
With alternator not working, no current is flowing in the output wire (R6). That wire becomes an extension of the meter's test probe.

A half volt drop between the battery and the welded junction (solid dot) with only 4-6 amps flow indicates high resistance between those two locations.

IF these measurements are all done at the same time, same conditions (engine running, alternator not working), this is a useful diagnostic.

If the voltage from the welded splice to ballast is also 11.8 volts, then there is little resistance between those two locations.
(or there is no current flowing. if the engine is running, then current must be flowing)

With key in run, nothing else on, Chrysler considered 0.4 Volt drop from the battery to the ballast as acceptable.
But this was measured directly so as to eliminate ground losses. So you could allow another tenth of a volt without getting too concerned.
The big question is whether power is getting to the alternator's field terminal. And if so, without a major loss.

If the regulator sees 11.4 or even 12.4 volts at the ignition terminal, it should allow full flow through to the alternator's field terminal.

A quick way to check if the problem is in the VR is to jumper from the VR ign to VR field terminal.

 

[67Dart273]

RE READ POST NUMBER TWO

 

[DH-66cuda]

if you go again, get a copy of the test print out.
Without that we don't know what the test(s) consisted of, so can't jusdge the results.

See Dana's comment about the fuses in the regulator.
(you can remove cover and check those on a mechanical regualtor)
Also, to better understand why that blew the fuses, look at the sticky titled Identifying Chrysler Alternators.

That should eliminate the likely blown fuse in the VR.

IF this was tested at same time as when the battery positive was 12.3 Volts, this suggests a signficant amount of resistance between the battery positive and the mainsplice, or poor grounding.

The voltage at that terminal should be very close to the same as the supply voltage.
IF these measurements are all done at the same time, same conditions (engine running, alternator not working), this is a useful diagnostic.

So some more info.. with jumper on fld to 12v side of battery the alt post goes up to 13.2.. I was not able to Rev the motor and test at same time to see if this increased more but is more than I was getting. I also checked the new VR I thought might have blown also and it has a blown wire just like the old one see image.. same blown wire on both.

So not sure what would be blowing the VR?

 

[Mattax]

It looks like that fusible link is the one to the upper contact?

If so, then something downstream of the regulator is drawing too much current.

Normal flow through regulator to rotor.

Short to Ground in the Field Circuit
If the output wire contacts ground, then there is no resistance and current flow becomes excessive.

Then the fusible link melts.

Remember the normal position for the arm is contacting the upper point.
Only when voltage is above 13+ Volts does the electromagnet have enough power to pull the arm down.

 

[DH-66cuda]

It looks like that fusible link is the one to the upper contact?

If so, then something downstream of the regulator is drawing too much current.

Normal flow through regulator to rotor.
View attachment 1716101699


Short to Ground in the Field Circuit
If the output wire contacts ground, then there is no resistance and current flow becomes excessive.
View attachment 1716101700

Then the fusible link melts.
View attachment 1716101701

Remember the normal position for the arm is contacting the upper point.
Only when voltage is above 13+ Volts does the electromagnetic draw enough power to pull the arm down.

Thanks again for the info... this is a little beyond me. Is there anything I should check to know why the VR line is blowing?

 

[Mattax]

Sooo.
The first two places to check for shorts are:
1. The wire from the regulator to the field terminal.
2. The field terminal to the rotor.

I would probably first measure resistance from the green wire's connector to the regulator, to ground.
This is just to see if I'm on the right path.
1. Then disconnect the green wire's connection at the alternator, and measure again. (a)
2. Measure the resistance between the alternator's field terminal and the alternator's housing (ground). The grounded brush will give the best reading. (b)

Try to find as clean of a location as possible for the probes.
Check the zero reading (touch the probes together) even if its a digital meter.

(a) There should be infinate resistance, no connection, between the green wire and ground.
(b) There should be measurable resistance between the field terminal and the ground.
- no resistance is a dead short. probably bad insulation at the field terminal brush
- for other resistance readings, I'll hae to dig up my notes. The shop manual has the resistance of the field windings from slip ring to slip ring. Then add some resistance for the carbon brush.

 

[Mattax]

this is a little beyond me.

It should make more sense when you understand the alternator operation.
I think the most succinct explanation I've done is in the sticky.
Pay most attention to the Grounded Brush Alternator in post 1 and 5.

Identifying Chrysler Alternators (1960-1976)

Roundback and Squareback refer to the style of housing. Roundback through model year 1969. Roundback for model years 1970-71 usually has a slightly different rear housing Squareback Revised Squareback Is most easily differentiated by the thin middle between the housings. Overall these...

www.forabodiesonly.com

The VR diagrams above and a full explanation can be found in the 1966 Chrysler Master Technicians Conference #11.
Available online here: Browse MTSC by Model Year – 1966 – MyMopar
There's also a filnstrip video.

 

[67Dart273]

KEEP IT SIMPLE AND GO RE READ POST NUMBAW TEU

 

[Dana67Dart]

KEEP IT SIMPLE AND GO RE READ POST NUMBAW TEU

We get it! we get it!

Read post number 2.

 

[DH-66cuda]

It should make more sense when you understand the alternator operation.
I think the most succinct explanation I've done is in the sticky.
Pay most attention to the Grounded Brush Alternator in post 1 and 5.

http://[URL]https://www.forabodieso...ifying-chrysler-alternators-1960-1976.475691/

[/URL]

The VR diagrams above and a full explanation can be found in the 1966 Chrysler Master Technicians Conference #11.
Available online here: Browse MTSC by Model Year – 1966 – MyMopar
There's also a filnstrip video.

So got back to this during the weekend.. ran new wire for field and jumped from VR ign to new VR FLD and get less than 12 at the alt field and nothing more than 12.3 at alt post even with increasing RPM.

 

[67Dart273]

So got back to this during the weekend.. ran new wire for field and jumped from VR ign to new VR FLD and get less than 12 at the alt field and nothing more than 12.3 at alt post even with increasing RPM.

GO READ POST NUMBER TWO!!!!

Now, let's keep it SIMPLE.

"Got a VR". WHAT does that mean? Did you get a 69/ earlier VR or a 70/ later VR?

Have you CHECKED that the alternator FIELD is drawing current? Get into the service manual, and there is a procedure to measure the field current, so along that lines, ...................

Check field continuity, jumper power into the field and be sure it is drawing current.

When I say JUMPER I do NOT mean to use ANY PART of the factory wiring!!!! I mean GROUND the field if it is isolated, and FEED 12V into it with a jumper wire.

IF IT WILL NOT CHARGE under that condition, MEASURE the output voltage RIGHT AT the alternator output post, WHY?? Because there could be a problem in the charge wire wiring on the path to the battery. And that has HAPPENED!!!

You MUST get this done FIRST so you can eliminate some items.

IF THAT WORKS, now re--connect the harness to the alternator and again, find out if you have any power going to the field (key on) and is there any actual current being drawn? If so, repeat the test.

On the older alternators you can easily jumper the two VR wires together and this JUMPERS full battery into the field which tests all I have said above, plus proves whether the factory harness is "good" and providing 12V to the field. THEN you can worry about the VR

THIS IS NOT THAT COMPLICATED NOR DIFFICULT, a little "simple thinking:"


You have basically TWO electrical circuits (69/ earlier circuit)

You have the ALTERNATOR OUTPUT. This (originally) goes from the alternator output stud, through the bulkhead (large black) to the big welded splice under the dash---to and through the ammeter (big black) out of the alternator (big red)...back out thorugh the bulkhead, through the fuse link, and to the starter relay stud, and to the battery

FIELD VR: For 69/ earlier, one end of the field should be GROUND. The single field wire (green) goes to the VR which MUST be grounded, to the IGN terminal, and this is 12V coming from the keyswitch "run" IGN1 circuit.

DIFFERENCE with 70/ later. EASY

Like the 69, you have switched 12V feeding the ign terminal of the VR WHICH must be grounded, out the GREEN field terminal and to one of the two field terminals on the (70 and later) alternator. The remaining field terminal gets switched 12V also from the igntiion "run" circuit, and is blue. The VR controls the "amount of ground" shall we say, to the field circuit, to control output

SO YOU MUST

1....Test and figure if the output circuit is OK
2....Test and decide if the field circuit is OK
3.....Test the alternator by "full fielding" it thus leaving the VR out
4....If all the above is good, and you can find no other, replace the VR.
5...In some cases a sulfated battery can cause issues, but will NEVER cause a "no charge" condition.

 

[Mattax]

So got back to this during the weekend.. ran new wire for field and jumped from VR ign to new VR FLD and get less than 12 at the alt field and nothing more than 12.3 at alt post even with increasing RPM.

Not sure why your quoting my post there. Seems your following post 2.
My suggestions, based on the melted link, were in post 15. Post 16 was where where to look for background info on how it works.