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Dan
Dan, Technician
Category: Chrysler
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Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Alternator not charging

Resolved Question:

alternator not charging
Submitted: 3 years ago.
Category: Chrysler
Expert:  Dan replied 3 years ago.

Welcome to JustAnswer, my name is XXXXX XXXXX I'm here to help get your problem resolved. Ask follow up questions, thanks.

 

The Power Train Control Module controls the field by duty cycling a ground on the control wire. The other field wire is fed by the Auto Shut Down Relay so it will only be powered when the engine is running. Test the charging system amperage output. It should be over 75 amps. If not, then replace the alternator. Monitor the field positive circuit for charging system voltage, once the engine is running, on the Dark Green/Orange wire. Use a scope to watch for drop-outs of voltage. Repair the wiring as needed. Verify there is nothing wired in to the Dark Green wire between the alternator and the PCM. Remove anything that is hooked to this circuit. Monitor the field control circuit (Dark Green) wire to the PCM. The voltage should be switching from battery voltage down to ground when viewed on a scope. Using a voltmeter will result in an average reading and not work for this test. So at the alternator 3 wires should have power and 1 wire should pulsate ground off/on, here is a wire diagram to help with tests. Let me know if you have quwestions, thanks.

 

graphic

Customer: replied 3 years ago.
the other mechanic rebiuld these things for a living. alternators and starters are all he does. he claims he had it out twice and tested it and its good. he says its in the pcm (voltage regulator). im not as good as you are with electrical but i learn fast. . but i need ya to put things in laymens terms for me to easier understand. also i dont have a scope. and only meter i have a a standard multi meter. ive never used it to check amps and im not sure how
Expert:  Dan replied 3 years ago.
At the alternator there should be two large wires and a smaller black/red wire...These wires should all have voltage with vehicle running so start by checking that. If good you will need to check resistance between pcm and alternator on the Blue wire. So just check resistance on the blue wire and make sure there are no opens or shorts.........If blue wire is good and the other ones have power when running then replace pcm. Let me know if you have questions, thanks.
Customer: replied 3 years ago.

ok i see the three wires. the black with orange stripe,,,the blue,,,, and then the main one that goes to battery. now there is no voltage at all comeing out of the main one to battery,, what kinda voltage should i expect on the blue and the bl?ornage wires?

 

Expert:  Dan replied 3 years ago.

 

The main one going to the battery should at least have battery voltage, if not follow wire and try to locate fusible link on wire. The blue one is pulsated ground off/on to control charging and the black/orange one should have voltage when vehicle is running. Let me know what they are, thanks.

Customer: replied 3 years ago.

i had 12 volts on the main wire while running, i beleive the black wire and the blue wire were around 11.7

 

Expert:  Dan replied 3 years ago.
The blue wire should be grounded so that shouldnt have voltage....The black/orange wire should have voltage....If you ground the blue wire while running or tap it off/on to ground then it should start charging....If so verify blue wire between alternator and pcm is good then replace pcm. Let me know if you have questions, thanks.
Customer: replied 3 years ago.

i may have been wrong about the blue but we definately had 11.7 volts to main wire and to black/orange wire with engine running. but shouldnt it be puting out 14 volts or better? would 11.7 volts just be reading the battery?

 

Expert:  Dan replied 3 years ago.
Correct, the 11.7 reading is just the battery.....But since it has battery voltage we at least know the wiring is good......So as of right now the problem is either the blue wire being open between alternator and pcm, or pcm being bad....if you tab blue wire off/on to ground alternator should start charging, if so check wiring between alternator and pcm and replace pcm if wiring is good. Let me know if you have questions, thanks.
Customer: replied 3 years ago.

are you saying to jump blue wire to ground?

 

Expert:  Dan replied 3 years ago.

Basically but not directly to ground, you dont want to burn up alternator....But if you tap ground off/on on the blue wire it shoudl charge. Let me know, thanks.

Customer: replied 3 years ago.

ok. i did just like you said and sure enough, as soon as i touch it to ground , she shot right up to 14 volts. so its definatley the pcm?

and if i get a used on from juk yard do they need to be flashed on this particular model?

 

Expert:  Dan replied 3 years ago.

First make sure that wire between alternator and pcm is good....If so, then its the pcm....I think you should be ok with a used pcm without having to flash. Let me know if you have questions, thanks.

Customer: replied 3 years ago.
well when i tested the blue wire by grounding it i did it at the pcm end of the wire. so the connection to alternator has to be good? right?
Expert:  Dan replied 3 years ago.
Correct, sounds like a bad pcm to me. Let me know how it goes, thanks.
Customer: replied 3 years ago.

dan. you are the man. im pretty sure thats what it is too. so im gonna accept your answer. theres an extra big tip in for ya if ya dont mind one more question about another car? ihave 00 taurus that starts and runs for about 2 seconds then dies. the security light is flashing.

 

Expert:  Dan replied 3 years ago.
Whats the 8th digit of the vin on the ford?
Customer: replied 3 years ago.
2
Expert:  Dan replied 3 years ago.
I'm really not sure about this one...I'm not all that familiar with ford security systems but as far as I know it shouldnt cause a start/stall....It would just cause a no start.....The mass airflow sensor can cause it to start/stall....You could try to disconnect the mass airflow sensor to see if it keeps running if so replace....If that doesnt help I'd open up a new question for someone who is more familiar with the ford theft systems. Let me know if you have questions, thanks.
Dan, Technician
Category: Chrysler
Satisfied Customers: 21582
Experience: Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
Dan and 2 other Chrysler Specialists are ready to help you
Customer: replied 3 years ago.
will do. thanks a bunch
Expert:  Dan replied 3 years ago.
No problem, let me know how it goes. thanks.
Customer: replied 3 years ago.
hey dan, on that ford, what its doing is when i turn the key to the start positon and hold it there. the starter actually starts and stops about three to four times then just stops again. the the only way i can get it to do it again is to pull the key and then put it back in and try again.
Expert:  Dan replied 3 years ago.
So it never completely starts? Starter just turns the engine a few times then it stops?
Customer: replied 3 years ago.

hey dan, on the sebring... i changed pcm. no luck. still not charging

 

Expert:  Dan replied 3 years ago.
Odd, Give me some time to look into this and ask around to see what other otions there are. Thanks.
Customer: replied 3 years ago.

hey dan. not tryin to be a pest, but have you heard anything yet.?

 

Expert:  Dan replied 3 years ago.
Did you check the battery output terminal on the alternator for battery voltage at alternator with key off? It should have battery voltage if not there is likely a blown fuseibile link. Let me know, thanks.
Customer: replied 3 years ago.

yes. i tried that. it was one of the first things i tried. what are the odds of the new pcm being bad? i mean as soon as i shorted out the blue wire i had a full charge???

are there any other components to the chargiing system that i am missing?

Expert:  Dan replied 3 years ago.

To me it seems like the new pcm may be bad since there really isnt that much involved in the system but I hate replacing brand new parts, especially pcm's......But if all the other wiring is good I'd say replace again.....You could also make sure the power/grounds on the pcm are good. Let me know how it goes, thanks.

Customer: replied 3 years ago.

which ones are the power/ grounds?

 

Customer: replied 3 years ago.

hey dan. i had another pcm shipped from a place in florida but it gave me a no start situation so i am sending it back. they asked me to ship them MY pcm since it starts the car they said they can fix the charging problem in it. but b4 i send it to em i wanted to know more about the possibility of the power/ ground wires. which ones are they and whats the best way to test em? please help. ive had this ladys car 2 weeks now. she's getting angry and im getting desperate. thanks

thom

Expert:  Dan replied 3 years ago.

Considering it charges when you ground the wire going to the pcm that shows that all of the other wires are good going to the alternator. Here is a connector diagram so you can test pcm power/grounds.

 

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Customer: replied 3 years ago.
ok pin #10 and pin#50 are grounds and they are good grounds. the only power supply im seeing is pin#44 (8 volt) is that with key on or off? pcm plugged in or not? and am i missing anything. those are the only three i see
Expert:  Dan replied 3 years ago.
46 is power, use a testlight when testing power/grounds.
Customer: replied 3 years ago.
yeah. good grounds and good power.
Expert:  Dan replied 3 years ago.
Ok, then the PCM being fixed should take care of the problem. Let me know how it goes, thanks.
Customer: replied 3 years ago.
hey dan. ive tried two remanufactured pcm's and i still cant get car to charge. alternator tests good and i can get car to charge when i jump the blue wire to ground it'll start charging. this is the second computer ive tried and still no luck. are there any other options
Expert:  Dan replied 3 years ago.
I'll ask a few other people, its appears we are overlooking something but the people I've had look at it so far had no new info for me..I'll send it to them now and ask me later if anyone said anything.
Customer: replied 3 years ago.
ok. im pretty desperate at this point. customer is getting upset and ive been at the mercy of the remanufacturers.
Expert:  Dan replied 3 years ago.
I hear ya, I just messaged a few people lets hope someone has some ideas......At the alternator there should be 4 wires going to it, correct? 2 large ones and 2 smalles ones...Out of them 3 should have voltage while running, do they?
Customer: replied 3 years ago.

i'll check again and get back to ya. been a week since i had it up in the air

 

Expert:  Dan replied 3 years ago.
Ok, because two lage wires go to fusible links which go to battery power....Then the small wire "not the one you ground" is powered by the ASD relay.
Customer: replied 3 years ago.

what is ASD and were is it?

 

Expert:  Dan replied 3 years ago.

Here is a picture but if this was the probelm other things would be effected to but it may be wire between relay and alternator.

 

http://i386.photobucket.com/albums/oo303/djenn434/Uploads/asd_0000.jpg

Customer: replied 3 years ago.

ok i found relay. any thing secific i can do to test the socket and the relay?

 

Expert:  Dan replied 3 years ago.
Also looking over conversation I dont see that you verified power at pin 46 of pcm connector . Start by checking for power at that connector of pcm and let me know.
Customer: replied 3 years ago.

using a test light with key off. pin 46 has power. do i test it with volt meter?

 

Expert:  Dan replied 3 years ago.
Ok, then everyting is fine as far as I know....There must be something I'm over looking...Lets wait to see what a few other experts think.
Customer: replied 3 years ago.

what about the ASD relay. should i look into that?

 

Expert:  Dan replied 3 years ago.
You shouldnt need to becauase if it wasnt providing the alternator power then grounding wire at pcm wouldnt allow it to charge.
Customer: replied 3 years ago.
i just double checked all voltage at alternator with vehicle running. there are only three wires. one big one and two small one. when i wiggled the blue one. i heard the engine surge. i think pigtail may have bad connection. but how does that work when i ground blue wire at pcm?
Expert:  Dan replied 3 years ago.
The pcm sends ground pulsations to the alternator which arent as strong as a direct ground so maybe the bad connection was enough to not allow the weak ground signal through,...Let me know.
Customer: replied 3 years ago.

ok with meter and engine running i push in on plastic housing of the pigtail that plugs into the back of the alternator and engine starts charging and when i relaes it it stops charging. im going to change pigtail but i don think thats it. i think its actually the female socket on the alternator itself thats bad

Expert:  Dan replied 3 years ago.
That what it sounds like to me, you should be able to use a screwdriver to push the femail connector together so its a tighter fit....wow, this was a strange one...definitly something learned.
Customer: replied 3 years ago.
yeah,, for both of us. i did the screw driver thing already and it didnt help. thats why i think it is the socket. i'll have it cxhanged in an hour or so and i'll let ya know.
Expert:  Dan replied 3 years ago.
Ok let me know how it goes, everything is starting to sound solid and I had some other people scratching the head too.
Customer: replied 3 years ago.
ok i changed pig tail. no luck. gonna change alternator. (which is what i think its is any way) will let ya know
Expert:  Dan replied 3 years ago.
Ok, let me know. Thanks.
Customer: replied 3 years ago.

ok. i changed the alternator and we are good. tell all you reinds and family LOL. i even took old alternator to have it tested and it still tests good. its just that socket that is bad

thankss for all your help and patience.

Expert:  Dan replied 3 years ago.
Happy to hear its working...its always hard to diagnose a probblem when testing new parts fail to show problems. Thanks again.
Customer: replied 3 years ago.

hey dan i need help with an electrical problem (dome lights) on a 96 cherokee your the man with all the electrical answers so if you can help me i'll open another question to you. only reason i went through this post is cuz i can never catch you online. this way when you respond to this. i'll get a text message letting me know you on. thanks

thom

Expert:  Dan replied 3 years ago.
Whats the problem with them? Thanks.
Customer: replied 3 years ago.

i replaced the drivers door on this 1996 cherokee with a used door off a 93. everything was identical. and i used ALL the parts from the old door.but for some reason. ever since i changed the door. the interior lights will not go off unlees the key is in the on position. i know all the switch at the doors work because the lights go on and off when i open and close all 5 doors one at a time. but only if the key is on. as soon as i turn the key off. BOOM all the dome & door lights come on. now i wanna make sure you get paid. so if you thnk you can helpme lemme know and i'll repost this as a new question

 

Expert:  Dan replied 3 years ago.
That is a strange one from what I see on the wire diagram the door inputs go directly to the body control module then body control module controls the lights....Have you tried to disconnect the battery and touch cables together for 10 seconds to reset module? If not try that and let me know, I think its a long shot but it might work.
Customer: replied 3 years ago.

touch what cables together? the pos and neg battery cables?

 

Expert:  Dan replied 3 years ago.
Yes, with battery disconnected this will resset the modules.
Customer: replied 3 years ago.
ok. i tried it but it didnt help. with door open and key on the door light is on of course. when i push in the button on the door jam it goes off. but only with key on. could it be in the dome light dim switch?.
Expert:  Dan replied 3 years ago.
I dont see anyway it could be related from the diagrams I see. Open up a question in jeep, maybe someone has seen this before because I woudlnt think the body control module failed just by replacing door.
Customer: replied 3 years ago.
i did open one in jeep. i waited 2 days and never got a response. any way. i still wanna throw some money your way. you wanna take on a 75 cougar im restoring. im have ing wiring problems with it also. i could use wiring diagram for ignition
Expert:  Dan replied 3 years ago.
I only have wire diagrams avbailable until about 84 so I woudnt be able to help there either. You will need to post a question in classic car and hope someone has a book for car or knows ignition system off top of head.

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Dan
Dan
Chrysler Mechanic
21582 Satisfied Customers
Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database