2000 Jetta charging system issues

The car hit 360,000 and I sent it in for timing belt and a new clutch. Along the way they ran into a few other things that needed replaced. I got the car back last Tuesday and drove it around 50 miles back to my house, and it felt brand new. Went to drive it two hours later and the ABS light turns on backing out of my driveway, then the airbag light comes on. By the time I got it turned around and back to the house the dash lights were very dim and my radio kept turning on and off. I charged the battery and took it to autozone to run the battery and alternator test. Battery checked out fine, but was too low to do a alt test. I assumed it was the alternator and spent an hour popping it off. Took it and the battery to advance and had them test them both, and both passed the tests....twice. I then took them to autozone and had them check each one and both passed. I put the alternator and charged battery back in. Was getting 12.59 volts with the car off and around 12.23 with car running. Drove the car 5 miles in town to return the new alternator I didn't need, and by the time I got home the ABS and airbag light came back on. I have checked battery connections, alternator connections, ground going to the engine, the fuse link from the battery to alternator, and all seem to be fine. I checked the battery voltage with the car off and it was around 12.15, then checked at the hot wire to the alternator and the plug to the alternator, both had matching voltages.

Any ideas?

Follow the cable from back side of alternator to fuse box on top of battery and see if the other end is hot to touch...the ends are known to get resistive.

I would take the car back to shop and have them figure it out.
Sounds like when the tranny was removed for the clutch install, one of your grounds​ weren't properly secure causing your problem.

bajan

catodd said:

Follow the cable from back side of alternator to fuse box on top of battery and see if the other end is hot to touch...the ends are known to get resistive.

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I actually checked that and it didn't seem to be hot to the touch.

red16vdub said:

I would take the car back to shop and have them figure it out.
Sounds like when the tranny was removed for the clutch install, one of your grounds​ weren't properly secure causing your problem.

bajan

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That is about where I am at right now.

Your charging voltage is to low. S/B about 13.5 with the engine running. With the age/miles of your car, I would suspect the regulator/brush assembly (about $40). If your bearings are good I would replace it.

Once you have the old regulator/brushes out,inspect the slip rings and replace them as well if they have extreme wear. Some disassembly is required to replace the slip rings.

https://www.idparts.com or one of our other vendors.

You should probably call them to get the right regulator/brushes.

Do not buy a replacement alternator from Advance, O'Reilly's etc. What they sell for alternators is garbage. I have had parts house alternators not work right straight out of the box.

I don't understand why people buy garbage parts. I smacked my R/H wheel real hard on a curb and the tire shop replaced the ball joint with one from O''Reilly's. Well it lasted less than 30K miles were the OEM ball joint on the left side is at 180K miles and still fine.

Ol'Rattler said:

Your charging voltage is to low. S/B about 13.5 with the engine running. With the age/miles of your car, I would suspect the regulator/brush assembly (about $40). If your bearings are good I would replace it.

Once you have the old regulator/brushes out,inspect the slip rings and replace them as well if they have extreme wear. Some disassembly is required to replace the slip rings.

https://www.idparts.com or one of our other vendors.

You should probably call them to get the right regulator/brushes.

Do not buy a replacement alternator from Advance, O'Reilly's etc. What they sell for alternators is garbage.I have had garbage parts house alternators not work right straight out of the box.

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The alternator is an autozone brand one that has been in there since fall 2012. I had autozone and advance auto test it out of the car, twice, and it checked out at both places for what it's worth.

I had an air bag light one time. It was a wire under the battery box. Cleaned them up, reset the fault lights and all was well after that. A vag com is indispensable for oddball problems.

Because your battery got low almost to the point of no voltage, you started to get dash lights, airbag, abs, etc. Get a multimeter and check your battery and charging system yourself. A healthy battery sitting in your driveway with the car off should read 12.6+ , with the car idling it should read 14+. If it's not reading more than 14 with the car running something is interfering with the charging process.

It could be a ground since you had all that work done, and the ground that had to be removed to do the clutch is the one right at the top of the bell housing. Take it off clean it up and tighten it back on. That might solve your problem.

From your description however it sounds like your alternator is running out of steam and either needs a rebuild or replacement. Most people opt for replacement over rebuild, and as already stated go for a new or rebuilt Bosch from a reputable source. I understand you had it tested, twice. Do a search on this forum and see how many people have done the alternator test at a parts store had it pass and it sill turned out to be a bad alternator.

Ol'Rattler said:

Your charging voltage is to low. S/B about 13.5 with the engine running.

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Should be more like 14.5v imho. My currrent two TDI's run between 14.5v and 14.6, and I've seen my Golf hit 14.7v on occasion. My previous two TDI's, and the gas VW's before that all ran mostly at 14.5v as well. My 2000 Beetle would be the only exception as it ran around 14.4v most of the time.

Rembrant said:

Should be more like 14.5v imho. My currrent two TDI's run between 14.5v and 14.6, and I've seen my Golf hit 14.7v on occasion. My previous two TDI's, and the gas VW's before that all ran mostly at 14.5v as well. My 2000 Beetle would be the only exception as it ran around 14.4v most of the time.

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Yeah, but you're measuring in Canadian voltages!

UhOh said:

Yeah, but you're measuring in Canadian voltages!

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Hahaha....yes, I suppose I am, aren't I?

Damn exchange rate.

Now you know why the US never went Metric! (things get lost in conversions!)

Just charged the battery up and got the car started. I checked voltage at the battery, then check voltage coming straight out of the alternator and it was the same. So I'm guessing that confirms there is no resistance problem and in fact the alternator is not putting out like it should.

For alternator rebuilds I deal with a company called alterstart in Texas. I've had cars with big radio systems that ran 130a alternators full out for hours at a time. 3 years of abuse and the car got sold with the alternator still working properly.


On the Canadian voltage comment. Don't use a Japanese voltage meter. Remember to them everything is 3/4 of what it really is. A rice cooker cup is a good example lol


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Rembrant said:

Should be more like 14.5v imho. My currrent two TDI's run between 14.5v and 14.6, and I've seen my Golf hit 14.7v on occasion. My previous two TDI's, and the gas VW's before that all ran mostly at 14.5v as well. My 2000 Beetle would be the only exception as it ran around 14.4v most of the time.

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My bad. Couldn't remember the exact number. 13.5 would be the in the realm of keeping the battery charged, 12v something would not. Now that I think about it, 14.5 V does sound better.

thirdgenracer86 said:

The alternator is an autozone brand one that has been in there since fall 2012. I had autozone and advance auto test it out of the car, twice, and it checked out at both places for what it's worth.

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Like I said, garbage. My factory alternator has 180K miles on it and is still fine. This summer I will probably change the regulator/brushes and slip rings. If you still had the OEM alternator laying around, changing the regulator and slip rings would probably bring it back to life. Or do like AnotherPerson suggested and have it rebuilt.

thirdgenracer86 said:

Just charged the battery up and got the car started. I checked voltage at the battery, then check voltage coming straight out of the alternator and it was the same. So I'm guessing that confirms there is no resistance problem and in fact the alternator is not putting out like it should.

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New alternator installed. Same issue, reads 12.xx without car running and 12.xx with it running. What tells the alternator that it needs to send power to the battery? I'm thinking the brain that tells it to charge, isn't telling it to charge.

Did you test voltage at the post on the back of the alternator?

Check the two wire plug on the alternator.should have voltage on one. Also follow the wires back toward the starter. There's a plug there with four wires two for alt and two for ac comp.sometimes can get corroded and have a bad connection.might have gotten unplugged when changing tranny.

Just an update. I took it back to the shop and they found out the problem. Was a broken wire that runs from the starter to the alternator. Thanks for the help, and maybe this will help others in the future.

along the same line , mine drops sometimes to just above 12 on my ultragauge then back to about normal if I turn the lights or heater fan on it when its low it jumps back to normal [13.8 or better] new alternator 6 months ago. I'm suspecting the regulator,
I checked and relocated the ground wire made sure I had good connections , red battery light has never came on sometimes abs and brake light does ?