E-Bodies.org Cuda Challenger Forum

Technical Shop => Electrical & Audio => Topic started by: Mopar94 on March 01, 2020, 01:55:53 AM

Title: Charging problem with new alternator
Post by: Mopar94 on March 01, 2020, 01:55:53 AM
Hello everybody !

I have trouble with my Chally  ::)

My alternator doesn't charges. (remanufactured)



I'tried :
I have bought a new regulator (grounded) = same

add a wire to ground the regulator = same

add a wire from the 12v battery to the blue wire to the regulator = same

unplug the green wire, and wire directly the FLD to ground = alternator charging full output ( 16/17V)

I'm lost...  :thinking:

I have a big wire from the alternator to the starter relay for bypass a little bit the circuit ammeter.

I don't think a cut wire, because when I plugged my other car on the battery (14v), all electrical works.


My measures with just key ON :

Battery : 11.82V
Blue wire : 10.9V
Green wire : 10.9V
Ohm regulator : 3.32omhs ( with 20K setting)




Any help ?


my apologies for my English I live in Paris :france:

big thanks in advance
Title: Re: Charging problem with new alternator
Post by: Cuda Cody on March 01, 2020, 07:47:09 AM
Have you had the alternator tested to see what it's putting out when in use?  Did the old and new alternators put out the same amps?

Is the battery good and able to take a charge?  How old is the battery?
Title: Re: Charging problem with new alternator
Post by: JS29 on March 01, 2020, 11:10:30 AM
Not looking to  :-[ my self, but shouldn't the battery at rest be producing 12.5 volts. he is telling us he has 11.82 I have had some strange problems that were related to a battery.  :alan2cents:
Title: Re: Charging problem with new alternator
Post by: BIGSHCLUNK on March 01, 2020, 07:23:56 PM
Like a bad alternator  :notsure:    :rofl:   Over the years I have seen bad ones right out of the box. (battery's too)   Get it charged then load test it (battery)
Title: Re: Charging problem with new alternator
Post by: Chryco Psycho on March 01, 2020, 08:10:39 PM
A good battery will read 13.4 v key off , key on it can drop into the 12 range so the battery is low & needs charging or is not good .
what voltage does it read when running ?
Title: Re: Charging problem with new alternator
Post by: Mopar94 on March 02, 2020, 03:03:54 AM
yes the battery needs to be recharged, But anyway, if I disconnect the battery when the engine is running, it shouldn't stop. This is the case here.


The measure while engine running are the same or almost, because the alternator doesn't charges.


As I said, if I ground one of the two connectors on the alternator, it works fine (16/17V), does that prove that it's okay?



I'm going to take the battery out, put it on charge at home.

Thank you all for your help. I appreciate it.



It's strange  :thinking:
Title: Re: Charging problem with new alternator
Post by: Chryco Psycho on March 02, 2020, 04:57:39 PM
Not the best way to test , the alt may not keep the engine running with the battery disconnected !!
But yes if the voltage is the same running or not the alt is not working , you should be 14.2-14.8 running , probably a bad diode
Title: Re: Charging problem with new alternator
Post by: MoparLeo on March 03, 2020, 11:57:41 AM
https://www.mymopar.com/charging.htm
https://www.allpar.com/history/mopar/electrical.html
What is the condition of your wiring harness and connectors ? Show us a picture of what you are working with. It makes it easier to help you. I have also included a couple of articles regarding older charging system that will help give you some detailed information. Read completely. It will help.
Title: Re: Charging problem with new alternator
Post by: Mopar94 on March 05, 2020, 08:41:04 AM
A bad diode, But it would still work under full load?



Thanks for the link ! I'm going to learn a lot of things

I'll let you know
Title: Re: Charging problem with new alternator
Post by: 73_Cuda_4_Me on March 05, 2020, 12:11:11 PM
My 73 would 'occasionally' not charge... driving down the road, and all the sudden the alternator would quit charging. Start it next day, and all would be fine (most of the time).

I found the wire pigtail connector plug going into the regulator had a bad wire just outside the molded connector, although the insulation on the wires were fine... the internal copper strands had broken right where the wire entered the molded plug that connects to the regulator.

I bought a replacement plug assembly and splice wired it into engine bay wiring, and no problem since (3 years).

Since you grounded field wiring and alternator went full charge, it sounds like the wires to alternator from regulator have a break or intermittent open... I found mine by moving the wires going into the connector at the regulator while idling... could hear engine lug when alternator kicked in when the wire made slight connection...

edit: Here is what I put on it to fix it....  https://www.summitracing.com/parts/pco-5329pt
Title: Re: Charging problem with new alternator
Post by: Mopar94 on March 05, 2020, 02:09:13 PM
Ok, so in your opinion, my alternator is OK ?


So I have to test my regulator connector, how can I test it ? without cut the wire, in first place.

I have already checked the continuity, from the regulator connector to the end, ( the connector FLD )   The wires are OK apparently.   Maybe the connector  :thinking:


I could buy a retro alternator with internal regulator, like powermaster, but it doesn't solve my issue, I prefer understand why it doesn't charges
Title: Re: Charging problem with new alternator
Post by: 73_Cuda_4_Me on March 05, 2020, 03:02:24 PM
I used some 600 grit wet or dry sandpaper rolled into a small cylinder, and put it inside the connector plug pins to polish any corrosion off the inside of the female pins in connector.

If you charge battery, then start engine, try wiggling the connector plug to regulator to see if engine loads down... that is how I found my issue.

I had continuity when unplugged, but when the wires were hanging when connected, it opened the wire strands enough to create the problem.

Move the wires around a little so they are coming straight out instead of just hanging down at a 90 degree angle, and see if makes a difference.

I used dielectric grease on the pins after swapping the connector to keep corrosion off pins...
Title: Re: Charging problem with new alternator
Post by: 734406PK on March 06, 2020, 06:24:03 PM
Quote from: 73_Cuda_4_Me on March 05, 2020, 03:02:24 PM
I used some 600 grit wet or dry sandpaper rolled into a small cylinder, and put it inside the connector plug pins to polish any corrosion off the inside of the female pins in connector.

If you charge battery, then start engine, try wiggling the connector plug to regulator to see if engine loads down... that is how I found my issue.

I had continuity when unplugged, but when the wires were hanging when connected, it opened the wire strands enough to create the problem.

Move the wires around a little so they are coming straight out instead of just hanging down at a 90 degree angle, and see if makes a difference.

I used dielectric grease on the pins after swapping the connector to keep corrosion off pins...

From your troubleshooting steps taken so far, it would appear to me that your issue is on the regulator side. Most likely the regulator harness has an open circuit in it. :alan2cents:
Title: Re: Charging problem with new alternator
Post by: dodj on March 06, 2020, 08:13:53 PM
Because you have full O/P afrom alt when you grounded the field, seems to be the VR to me. My first move would be to ensure the case of the VR is grounded well. Then ring out the wires, if the wires/connectors are fine, replace the VR. Don't overlook the connector along the valve cover between the alt and VR.
:alan2cents:
Title: Re: Charging problem with new alternator
Post by: Mopar94 on March 30, 2020, 02:31:08 PM
Thanks everyone for your answers.

I'm sorry for my absence, I was out of town for business and on vacation in New York for a week. ( Awesome trip, first time in USA  :unitedstates: )


So, my VR is brand new, I don't think it's faulty. ( 8ohms resistance on my multimeter)  It's grounded, because I can put the alt in full charge with the ground of the VR case.

The pigtail is apparently OK, If I move the wires, or the pigtails it makes no difference.

Brand new VR faulty ?  :huh:


I have ordered an internal regulator conversion to one wire for my alt. but That doesn't tell me the problem
Title: Re: Charging problem with new alternator
Post by: Brads70 on March 30, 2020, 02:55:35 PM
Quote from: Mopar94 on March 30, 2020, 02:31:08 PM
Thanks everyone for your answers.

I'm sorry for my absence, I was out of town for business and on vacation in New York for a week. ( Awesome trip, first time in USA  :unitedstates: )





:o   Yikes couldn't have picked a worse time to visit NY  , I hope you didn't pick up anything.
Title: Re: Charging problem with new alternator
Post by: Mopar94 on April 08, 2020, 03:15:47 PM
No I'm fine  :fingerscrossed:

it was the last week that everything was still going well there.