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Alternator or Voltage Reg or Something else?


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ewilli17
Novice

Aug 28, 2020, 6:36 PM

Post #1 of 10 (230 views)
Alternator or Voltage Reg or Something else? Sign In

2004 PT Cruiser ...alternator charges battery then quits and car runs off battery until dead...but if I turn off car and restart, it will charge battery then quit again.
Alternator is few years old...when running its runs at 14.3V...battery is new...all wires that I can see and tested have no power loss of grounding issues...
Last thing I can think of is voltage regulator in PCM is going bad...and ideas before I try a bypass voltage regulator.

Thanks in advance for help :)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 28, 2020, 6:39 PM

Post #2 of 10 (228 views)
Re: Alternator or Voltage Reg or Something else? Sign In

This problem is diagnosed through testing, not "ideas".

How do you plan on "bypassing" the PCM?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ewilli17
Novice

Aug 28, 2020, 7:56 PM

Post #3 of 10 (207 views)
Re: Alternator or Voltage Reg or Something else? Sign In

I looking for idea's of something I may have missed. I have tested wiring, voltages and ohms from alternator, PCM, grounds...I trying to get a idea why the alternator quits supplying to car after battery is charged...so I don't have to install external regulator if that's what it is...last thing I can think of a the moment.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 29, 2020, 3:53 AM

Post #4 of 10 (195 views)
Re: Alternator or Voltage Reg or Something else? Sign In

Some thoughts OP before you get into any tricks - a question 1st and test for you:
Quoting you that alternator is a "few" years old - duly noted. Chances are (up to 4 clones within several months) this is a clone job was dirt cheap vs a true reman that was well done seems gone with the wind! Tried to do a few failed to get internal parts myself and do them! One (assorted makes mind you) I did have parts for on hand works fine again - just about what you are seeing with 14.3 after a start up then a problem.
It could be just plain brushes (cheap crap on clones) still a maybe test to try.
Find or make a wood something to be out of the way of anything to harm to strike with a hammer at body of alternator if impossible don't. Idea is heat (about anything for decades) is too much under hoods I think the problem and has been hot on top on hot in many places.
So when it quits after behaving then - AYOR while running and watching voltage seems you are good checking this, strike (don't smash it to bits) alternator and see if it snaps out of it.


If not that is inconclusive if it works again and settles down from the 14.3V the idea kicks in.
It would be your call to do this at all think you could: Take alternator out and apart look right at brushes, springs the shaft brushes ride on. Bet it's all discolored and or brushes don't slide with springs very well? Need 3 hands to watch this.
Clean it all up if time and the will. Light high grit wet/dry cloth "600" I think sand paper or higher # just shine off the brass contacts if enough brush carbon is left (have to just know what is normal or forget it) then re-install and check it. Load it and unload with lights, blowers, electric defrosters and watch it.
Sorry for the novel I'm so ticked at new or remans have had this work on the few for years is better than what you may find new WAS ALSO TOLD BY MY AREAS REBUILDER that's all they do sometimes!
The rest of remans is making it look nice in a box again - ticked off by this as I think you can tell AYOR if time to do that,


Tom



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 29, 2020, 4:25 AM

Post #5 of 10 (190 views)
Re: Alternator or Voltage Reg or Something else? Sign In

Have you put a professional scanner on this thing? Any codes?

If the charging circuit fails in the PCM, it should set a code.

How about the battery temp sensor? Have you monitored that in the scanner when the problem occurs?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ewilli17
Novice

Aug 29, 2020, 9:24 AM

Post #6 of 10 (169 views)
Re: Alternator or Voltage Reg or Something else? Sign In

Thanks for reply...I get ya...No clone/remanf job...quality new alternator installed, because didn't want to do twice since its a pain in the a@# to do and still looks new/clean as day installed, inside and out.

But yeah still on the list as possible issue...as things fail.


ewilli17
Novice

Aug 29, 2020, 9:48 AM

Post #7 of 10 (169 views)
Re: Alternator or Voltage Reg or Something else? Sign In

Thanks for reply...Yes, dealership quality scanner monitored alternator charging battery then crapping out letting car run of battery until car is shut off and restarted, this resets whatever causing issue...that's why I'm thinking electronic (a sensor as you stated) because it does reset after turning off and on engine.

I agree...I wish it would throw a code, but no codes and all sensors performing within thresholds per scanner...during startup, at idle and driving.

It's one of those deals where everyone wants to throw parts at it until fixed...one pro mech says PCM as alternator checks out and another says alternator is failing.

I'm thinking a external voltage regulator will help eliminate one or the other or both, so I don't just throw expensive parts at it and hope for the best...I hate that.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 29, 2020, 10:13 AM

Post #8 of 10 (165 views)
Re: Alternator or Voltage Reg or Something else? Sign In

What sort of external regulator would you use? I've done a few of these.

You should be able to "full field" this during the non-charging period to either confirm or eliminate the PCM.

It IS supposed to set a code if the regulator quits.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Aug 29, 2020, 10:14 AM)


ewilli17
Novice

Aug 29, 2020, 12:20 PM

Post #9 of 10 (151 views)
Re: Alternator or Voltage Reg or Something else? Sign In

Yes sir...that's the plan...ground out the alternator to produce max voltage as a test...I have a Mopar regulator set at 14.3V and running a line to fuse box so it turns on and off with car.

I also have a friend that has a battery temp sensor which matches mine...going to swap and test his ohm range as well, just for giggles...I just tested mine again myself and it ranged from 7k-11k ohms...so looks good to me.

I agree...should have codes for all these situations...but check engine light has never came on to throw one, pre-code or history. Just the battery(alternator) light.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 29, 2020, 12:27 PM

Post #10 of 10 (149 views)
Re: Alternator or Voltage Reg or Something else? Sign In

Remember, you have an intermittent problem so these things have to be tested when the problem is present.

You should also be able to read the battery temp sensor data with the scanner.





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Aug 29, 2020, 12:35 PM)






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