# Bad Alternator? VW SUCKS



## steinosaur (Oct 15, 2009)

JK, i love this thing. . Gotta pay to play right. Anyway since i got the car pretty much i noticed the interior lights did not want to turn on right away. So i was like whatever kept on trucking. Then noticed that while the headlights and interior lights were on if i lifted up the window switch the lights would dim, strange, but ok nvm, i thought maybe bad grounds or something. Now today i notice a whine from the radio area, i decide to try out the up window switch trick, and bam the lights go out ABS and ASR lights are. I release the switch and its back to normal, although the interior lights are kinda dimming in a pulsating manner. I vag-d the car last week and got codes for airbag voltage to low and central control module for central convenience was faulty. So that being said. IS it likely that its all due to the cenetral control module being bad, or do you guys think its the alternator?


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## sgrass001 (Apr 3, 2010)

Check you main charge cable bro.. if your battery light is not coming on for a few seconds on the dash when you turn the ignition on then the cable is not allowing enough current to get to all the electronics. I bet if you take your battery and tray out and check the cable from the battery to the main engine harness you might find a toasty wire.. good luck..


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## steinosaur (Oct 15, 2009)

sgrass001 said:


> Check you main charge cable bro.. if your battery light is not coming on for a few seconds on the dash when you turn the ignition on then the cable is not allowing enough current to get to all the electronics. I bet if you take your battery and tray out and check the cable from the battery to the main engine harness you might find a toasty wire.. good luck..


 good suggestion, ill do this asap. Im also gonna get volt readings tmmrw.


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## steinosaur (Oct 15, 2009)

*Update: Multi meter readings*

Allright just got a multimeter to the car. Was reading over 12 volts while the car was off and 14.5 volts when the car is on and running. Did notice 1 volt drop when fiddling with power windows, not sure if thats too serious a drop, either way it looks like im looking at bad grounds or a wiring issue.


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## 18T_BT (Sep 15, 2005)

sgrass001 said:


> Check you main charge cable bro.. if your battery light is not coming on for a few seconds on the dash when you turn the ignition on then the cable is not allowing enough current to get to all the electronics. I bet if you take your battery and tray out and check the cable from the battery to the main engine harness you might find a toasty wire.. good luck..


just like this guy said, check the fuse block above the battery, to make sure all wires are in there nice and tight and not burned...it's probably your battery not your alternator


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## steinosaur (Oct 15, 2009)

18T_BT said:


> just like this guy said, check the fuse block above the battery, to make sure all wires are in there nice and tight and not burned...it's probably your battery not your alternator


yea i've checked those, they all seem to be fine


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## BassNotes (Mar 16, 2005)

Probably more alternators get replaced not because they're bad but because of crappy electrical connections.

Make sure that when you "check" connections, you actually check them.

One frequent problem spot on Mk4's is here. Measure voltage between these two points (stick the point of the voltmeter probe right through the insulation) with the engine running and the headlights and other electrical accessories on:









Also measure between the alternator body and the - battery post.

You should read a voltage drop of less than 0.1 volt, and preferably less than 0.05 V. If you measure more than that, you have a bad connection in between those two points.

In addition to the location in the pic, the ground connections (at bellhousing, at chassis under the battery, and at the - post) are frequent problem spots.


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## steinosaur (Oct 15, 2009)

BassNotes said:


> Probably more alternators get replaced not because they're bad but because of crappy electrical connections.
> 
> Make sure that when you "check" connections, you actually check them.
> 
> ...


Allright I'll get on that, and when you are reffering to a drop less than 0.1 you are talking about while measuring between the alternator body and the battery post correct? Thanks a lot for the help. Vag-Com said my CCM was faulty, besides the harness going into the actual ccm are there any other wires besides the one you listed to look out for in regards to that? I have a suspission its all related.


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## BassNotes (Mar 16, 2005)

steinosaur said:


> when you are reffering to a drop less than 0.1 you are talking about while measuring between the alternator body and the battery post correct?


Yes--there, and also at the points in the photo. That ring terminal at the end of the alternator + lead is a frequent failure point in Mk4 electrics, and it causes low voltage and melted fuse panels.

On my car the terminal caused a drop of about 0.5 V and used to get so hot it felt like a soldering iron, so I cut it off, stripped back the insulation on the alternator lead, made sure the copper was nice and clean and then crimped on a new copper ring terminal:










That solved the problem. The battery charges much more reliably, lights don't flicker and dim any more, and that terminal doesn't get hot any more.


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## sgrass001 (Apr 3, 2010)

I agree about checking the voltage on the terminal in the pic posted as I have seen this be an issue on other VW's. Just a note though.. the black cable coming off that fuse block on top of the battery runs down and connects to alternator but a small 16 gauge wire is tied into it and runs back up the main harness into the car and up to the guage pack. Double check that line. My cable was fine but that little wire is tied to the charge circuit on the alternator and tells the ECM to allow charge back to the battery. The wire will look green and melted if bad and not have current when backprobed...


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## steinosaur (Oct 15, 2009)

sgrass001 said:


> I agree about checking the voltage on the terminal in the pic posted as I have seen this be an issue on other VW's. Just a note though.. the black cable coming off that fuse block on top of the battery runs down and connects to alternator but a small 16 gauge wire is tied into it and runs back up the main harness into the car and up to the guage pack. Double check that line. My cable was fine but that little wire is tied to the charge circuit on the alternator and tells the ECM to allow charge back to the battery. The wire will look green and melted if bad and not have current when backprobed...


ok thanks a lot, you guys have been money. its raining ice right now so wont be able to check stuff till tmmrw, ill let you know how it goes, when checking these wires should i check while car is idling and then switch on all accessories to see what's happening?


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## radlynx (Jan 4, 2007)

keep us posted. I'm getting this same problem, when the headlights are on, and flick the window switch, the light dims. My interior lights doesn't turn on at all when I open any door, however the light turns on when I manually turn it on. based on my research here, they said that it's the Central Control Module. I already have the replacement part but have not installed it yet. I'm checking the wiring as well per the instruction above.



steinosaur said:


> JK, i love this thing. . Gotta pay to play right. Anyway since i got the car pretty much i noticed the interior lights did not want to turn on right away. So i was like whatever kept on trucking. Then noticed that while the headlights and interior lights were on if i lifted up the window switch the lights would dim, strange, but ok nvm, i thought maybe bad grounds or something. Now today i notice a whine from the radio area, i decide to try out the up window switch trick, and bam the lights go out ABS and ASR lights are. I release the switch and its back to normal, although the interior lights are kinda dimming in a pulsating manner. I vag-d the car last week and got codes for airbag voltage to low and central control module for central convenience was faulty. So that being said. IS it likely that its all due to the cenetral control module being bad, or do you guys think its the alternator?


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## sgrass001 (Apr 3, 2010)

When checking voltage at the terminal on top of fuse block the car must be running of course but to check the charge indicator wire on the main harness you will have to remove the battery, try and anything else in the way to check the harness for burn wires..


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## BassNotes (Mar 16, 2005)

sgrass001 said:


> I agree about checking the voltage on the terminal in the pic posted as I have seen this be an issue on other VW's. Just a note though.. the black cable coming off that fuse block on top of the battery runs down and connects to alternator but a small 16 gauge wire is tied into it and runs back up the main harness into the car and up to the guage pack. Double check that line. My cable was fine but that little wire is tied to the charge circuit on the alternator and tells the ECM to allow charge back to the battery. The wire will look green and melted if bad and not have current when backprobed...


That small wire is connected at the back of the alternator?


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## steinosaur (Oct 15, 2009)

sgrass001 said:


> When checking voltage at the terminal on top of fuse block the car must be running of course but to check the charge indicator wire on the main harness you will have to remove the battery, try and anything else in the way to check the harness for burn wires..


word, gonna try and get this done friday or thursday


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## sgrass001 (Apr 3, 2010)

BassNotes said:


> That small wire is connected at the back of the alternator?


That wire is actually part of the charge harness..if you are staring at the fuse block on top of battery it is the large black wire on the far left.. follow it down.. one side goes to alternator and then you will see a couple connectors on it also.. if you follow it under the battery try it goes to a main connector and there is a wire that actually continues into the main harness into the car..that is the charge indicator wire coming from alternator


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## BassNotes (Mar 16, 2005)

OK, let me phrase it this way: the small wire is connected to the alternator harness at the back of the alternator? Is that correct?


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## radlynx (Jan 4, 2007)

did you get to fix this problem? please keep us posted. thanks.



steinosaur said:


> word, gonna try and get this done friday or thursday


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## sgrass001 (Apr 3, 2010)

BassNotes said:


> OK, let me phrase it this way: the small wire is connected to the alternator harness at the back of the alternator? Is that correct?


Yes that would be it..


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## NEWBWITBEWBS (May 13, 2009)

*Same Problems, same car!*

Friend of mine is going threw the same thing. Had the alternator replaced and found one of the wires was getting super hot!! Husband (who is being deployed to Kuwait and knows VW. I know NOTHING of them..) had fixed the wire problem, but now the light is coming back on with no obvious future problems YET. I don't even know where to start to even help her. I guess I am looking for a good VW mom and pop shop. :banghead:


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## koke382 (Mar 18, 2011)

My 02 GTI is doing the same sh**** to me right now! i drive the car and then out of no where my lights turn off then on and my stereo does the same. After i turn off the car and try to turn it back on it wont and my dash clock re sets then it turns on, then the same sh** all over again!
I took it to the shop and they came back with Central Control Module for Central Convenience faulty codes and said it would be 580 to replace it ??? But cannot guarantee it would work?? so i left cuz i dont sh**t money lol, now today i was stranded because i pulled into a liquor store and when i came back my car wouldnt start and this time the dash warning lights came on and didnt turn off ??? :/
I love my VW but im haitng it right now :/
HELP


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## BassNotes (Mar 16, 2005)

What shop did you take it to? Maybe you need one that knows VWs and electricity?


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