Battery not charging emergency

charlieruu

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Marquette, MI
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2002 Jetta TDI Automatic, 239,000 miles
Hey all, yesterday I went to start my car and the battery was dead so I got it jumped and all was good. Later that night I was driving around and the immobilizer light was flashing at me followed by the airbag light. I've had this happen before when my alt died on me except that time the alternator light was on. I checked the voltage while running on my scanner app and it was at 9.4 volts. It recently got very cold here (under 0 degrees F) so I'm thinking something stopped working or broke because of this. I tried to check today to look for any loose connections and there were none. The battery is fairly new from VW dealership and the alternator is also new (<7k miles). The positive battery cable has also been replaced. This car has given me so many problems with not charging and I'm not sure what to do this time. I fear that a shop will just tell me I need a new alternator and maybe I do but I want to rule as much out as I can. Where should I start?
 

jettawreck

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Sounds like the alternator (or the internal regulator) is done. Nothing beats a physical bench test to check how it handles a load and output.
 

Mongler98

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Get volt meter, and test it yourself, or take it to auto zone and have it tested.
A volt meter with an amp draw function will tell you everything you need to know. If your battery is good, cables bad, connections, charging and so on. $10 bucks usually will do.
 

JesseTDI

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Most alternators and batteries have 12month 12k mile warranties you might get it replaced under that coverage if your lucky.
 

Mongler98

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Most alternators and batteries have 12month 12k mile warranties you might get it replaced under that coverage if your lucky.
I hate non OEM parts but some times, its worth going with parts with these warranties especially when OEM parts are hard to come across same day.
Case in point, my 04 escape EATS starter motors about every year or 2. Napa has a no hassle life time on all there parts. The guy i purchased the escape from back in 2014 had put it in. I have his folder of all the receipts and work done, took the starter in with the receipt, new starter for free, and have done this twice now. never pay for this part again. Granted it did leave me stranded 450 miles away from home once, BUT i was next door to a NAPA and had to wait till they open.
 

joetdi

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2-2002 Jettas W/Auto
Get volt meter, and test it yourself, or take it to auto zone and have it tested.
A volt meter with an amp draw function will tell you everything you need to know. If your battery is good, cables bad, connections, charging and so on. $10 bucks usually will do.
Your're going to need a little more than a volt or amp meter to test this. You need to put a draw on the alternator.
 

Ol'Rattler

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2006 BRM Jetta
Your're going to need a little more than a volt or amp meter to test this. You need to put a draw on the alternator.
The OP has 9.4 volts charging voltage. Is there some magical test equipment that would tell him why? What would this test equipment draw? a picture of Mr. McGoo?
 

joetdi

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2-2002 Jettas W/Auto
The OP has 9.4 volts charging voltage. Is there some magical test equipment that would tell him why? What would this test equipment draw? a picture of Mr. McGoo?
You full field the alt to see if all you need is a reg and not also a stator or retifier.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Your're going to need a little more than a volt or amp meter to test this. You need to put a draw on the alternator.
9.4 amps, regulator is bad or a soldering point within the unit.

Rebuild or replace.
no load drawing needed to test this.
 

Ol'Rattler

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Reg is not going to a help a bad stator.
Why do you assume that a low charging voltage is because of the alternators rectifier diodes? Still, an ohmmeter would tell you if you have diodes shorted or open.

If you want to replace the whole alt you could do that

A lot of people replace there OEM alternators with garbage re-mans and end up replacing those garbage remans time after time after time when they could have polished the slip rings, replaced the brush/regulator assembly and clutched pulley on their OEM alternator and been good for at least 100K miles more.

No, you don't need a crap ton of diagnostic equipment if you understand how things work and how to troubleshoot those things. One of the most bogus diagnosis tools I have heard of is the bull **** battery load tester auto parts stores have. The only way it's test is valid is if you have a battery charged 100% prior to testing.
 
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Ol'Rattler

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9.4 amps, regulator is bad or a soldering point within the unit.
Rebuild or replace.
no load drawing needed to test this.
Right arm Bro. At 9.4 Volts, no need to make something simple and obvious into a science experiment. If an alternator does not develop 12+ volts, how would the added stress of a load test give you diagnostic data that would lead to repairing the problem? In such a situation, you might find that the brushes are shot and arcing which will destroy the slip rings even more when you load up the alternator with your not needed load test.

And that's the problem with VCDS. So many people will shout to the stars about how completely awesome and necessary VCDS is and will have absolutely no clue into how to actually diagnose something even with the invaluable information VCDS provides.

For those that don't know, VCDS does not tell you what to replace. It tells you what the ECU sees that you need to diagnose to find out why the ECU set the code.
 
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Ol'Rattler

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Almost forgot. How is your battery not charging an emergency to anyone but you?
 

joetdi

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Midwest
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2-2002 Jettas W/Auto
Apparently you don't know what full fielding an alt does, with respect to the reg as you don't need a fully charged battery.

A guy next to me was working on a like vehicle as mentioned here. He measures about 9.6 volts. So based on Mongler's statement above he puts a OEM alternator on the car. He measures 9.8 now. So, it must be bad one right? So, he puts another OEM on and now he's really close to 10 volts.

What you think was wrong with this car and how did he find it.

And no it wasn't another bad alternator.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Apparently you don't know what full fielding an alt does, with respect to the reg as you don't need a fully charged battery.
A guy next to me was working on a like vehicle as mentioned here. He measures about 9.6 volts. So based on Mongler's statement above he puts a OEM alternator on the car. He measures 9.8 now. So, it must be bad one right? So, he puts another OEM on and now he's really close to 10 volts.
What you think was wrong with this car and how did he find it.
And no it wasn't another bad alternator.
DO tell!
sounds like a blown fuse, possible short on the wiring harness, possibly a parasitic draw of crazy proportions! i don't have a clue as these things are difficult to tell even with the proper equipment, it takes a qualified and specialized person to be present at the car with a good set of tools and know how to determine odd issues like this. You cant expect anyone on the forums to say " this is the problem" and it be that problem 100% of the time. But i can say that 99.9% of the time when you have bad voltages from an alternator and it was tested properly that the diode is bad.
 
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joetdi

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Look fellas, this guy implies that the alternator light is not on in his first post. If there is an open circuit in the wire to the light the alternator is not going to charge the vehicle and the battery will go dead. And his voltage will drop.

Or do you think he should risk replacing the alternator first and THEN see if the wire is open.

Ya, it is a simple system but why am I the only one that seems to see this. He needs to confirm that first and then there are other possible causes to.

He needs to turn the key on see if the battery light comes on and if not, ground it at the alt and see what happens. If the light still does not come on you got a problem. And it won't be the alternator.
 
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jayb79

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Exeter,NH
Well, it seems that this "emergency" is not all that important to the op as he has yet to reply to his "emergency". So, for now, I would just let it go until he replies to all the excellent feedback he has so far.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Look fellas, this guy implies that the alternator light is not on in his first post. If there is an open circuit in the wire to the light the alternator is not going to charge the vehicle and the battery will go dead. And his voltage will drop.

Or do you think he should risk replacing the alternator first and THEN see if the wire is open.

Ya, it is a simple system but why am I the only one that seems to see this. He needs to confirm that first and then there are other possible causes to.

He needs to turn the key on see if the battery light comes on and if not, ground it at the alt and see what happens. If the light still does not come on you got a problem. And it won't be the alternator.
Because testing the the voltage output of the alternator will tell you if that is the issue. I dont care how many dead batteries or open circuits are in the car, the alternator is either putting out 13ish volts or it is not.
 

joetdi

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Midwest
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That's how much you know.

Oh my, I hope that an open ground circuit to this alternator light is not this guy's problem because if it is, he is going to put an alternator on this car and be pissed.

It's not just you, there are a few others here that seem to think that the only thing this can be is a alternator. If you guys don't think that an open ground for the light can cause the problems he's having I can't help ya. The alternator on that car works the same as any other over the last 50 years.

OIL HAMMER, HELP, I'M NOT GETTING THIS ACROSS TO THESE GUYS THAT THIS COULD BE AN OPEN CIRCUIT, IT COULD BE OTHER THINGS TO BUT, THEY WANT TO PUT AN ALTERNATOR ON THIS CAR BEFORE CHECKING THIS AMONG OTHER THINGS THAT COULD CAUSE THIS. THEY ALL SEEM TO AGREE THAT THE ONLY THING THIS CAN BE IS AN ALTERNATOR. MAYBE THEY WILL LISTEN TO YOU.

I done with this.good bye.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
That's how much you know.

Oh my, I hope that an open ground circuit to this alternator light is not this guy's problem because if it is, he is going to put an alternator on this car and be pissed.

It's not just you, there are a few others here that seem to think that the only thing this can be is a alternator. If you guys don't think that an open ground for the light can cause the problems he's having I can't help ya. The alternator on that car works the same as any other over the last 50 years.

OIL HAMMER, HELP, I'M NOT GETTING THIS ACROSS TO THESE GUYS THAT THIS COULD BE AN OPEN CIRCUIT, IT COULD BE OTHER THINGS TO BUT, THEY WANT TO PUT AN ALTERNATOR ON THIS CAR BEFORE CHECKING THIS AMONG OTHER THINGS THAT COULD CAUSE THIS. THEY ALL SEEM TO AGREE THAT THE ONLY THING THIS CAN BE IS AN ALTERNATOR. MAYBE THEY WILL LISTEN TO YOU.

I done with this.good bye.
I, and most others here, never actually said to replace the alternator. We said to test it with a multimeter and to diagnose what’s going on and how OP can go about doing it.
While you are right in what you’re saying about an open circuit to the cluster light, what you are not understanding or are blindingly raging against is the fact that you can in fact disconnect the alternators 3 or 4 pin wire harness, and for that matter ALL THE WIRES even to the battery, start the car, and test the output of the alternator. THIS is how it is done at auto shops including autozones alternator testing rig. It simply and ONLY measures the output voltage and its sign wave and gives it a load draw amp check for kicks.
If OP just puts his probe leads on the battery and gets 9 some votes, sure it can be a few things, we check for the most common and work back from there.
I hate throwing money at a problem; you should know that if you have read my posts or my threads.
What you seem to do is argue about a point that nearly none of us have made. I did say that parts with warranties are great in the right application but I rather go EOM but I did not say to just buy a new part.
You are getting across plenty to all of us, and it feels like your just being a, well you know.
And as for the last 50 years, well most cars back then ran on generators, not alternators. And when alternators did come out to the world, it was back in the 1960's and they were NOT controlled like they are now and I can tell you that all the OEM alternators from the 70's (well in the cars I have owned and worked on) No they only had a ground and a charging wire. I’m sure some may have but you’re kind of going off the deep end here with exaggerations and ALL CAPS. No need to yell dude.
Glad to see you’re done, as am I, and so should this thread because OP has yet to respond. I’m sure he went to AutoZone and got a new part and it fixed it and he abandoned this thread. LOL
 
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BobnOH

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Location
central Ohio
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New Beetle 2003 manual
Apparently you don't know what full fielding an alt does, with respect to the reg as you don't need a fully charged battery.

A guy next to me was working on a like vehicle as mentioned here. He measures about 9.6 volts. So based on Mongler's statement above he puts a OEM alternator on the car. He measures 9.8 now. So, it must be bad one right? So, he puts another OEM on and now he's really close to 10 volts.

What you think was wrong with this car and how did he find it.

And no it wasn't another bad alternator.
Dead cell. This is why we test them the way we do. Voltage gives really good clues, often all you need, but it's not conclusive.
 

joetdi

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good choice, arguing with mongler is wasted effort, he will not learn anything
Ya, I don't why I do. He will tell you he never said something but you look back in his post and there is.

I think if you told him that if someone falls in a hot tub full of water they would come out wet but, he could post 3 paragraphs telling you why this person would be dry.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
you still have not told us what it was, and im not wrong. boss alternators and for that matter any alternator that i know of (in working order) will output 13-14 volts regardless if there hooked up to something or not.
prove me wrong or step off my back.
Also it seems you want to start stuff here. you guys should be messaging in PM, NOT in forum posts about any user here. its not nice, and definitely does not help the thread.
What at all in this thread am i wrong about? Show me, if i am, i will admit it 100% and eat my humble pie.
 

Ol'Rattler

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OIL HAMMER, HELP, I'M NOT GETTING THIS ACROSS TO THESE GUYS THAT THIS COULD BE AN OPEN CIRCUIT, IT COULD BE OTHER THINGS TO BUT, THEY WANT TO PUT AN ALTERNATOR ON THIS CAR BEFORE CHECKING THIS AMONG OTHER THINGS THAT COULD CAUSE THIS. THEY ALL SEEM TO AGREE THAT THE ONLY THING THIS CAN BE IS AN ALTERNATOR. MAYBE THEY WILL LISTEN TO YOU.

I done with this.good bye.
To funny. Help Mr. Wizard!!!!!! No one, even me, understands what I'm saying because I can't read and understand written English!!!!

I know it has bin implied that above all else the problem should be fully diagnosed, but I just can't believe that is what the other posters meant.
 
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