No Battery Light - Not Charging

Okay, I've been snooping around here for a couple of years but this is my first post.

When my 2001 Jetta 1.9L with no major mods quit charging the first time (about a year and a half ago) I got all the info I needed at this forum to diagnose the Voltage Regulator and R/R the Alternator. Thank You for that! I bought the cable from Ross-Tech and got VCDS and have solved a bunch of other problems.

This time has me stumped. The Jetta has been out of service for about 40 days and I am getting desperate. I've read as much as I could find here about this problem but wanted some advice before buying anything.

One day after pulling up into the driveway and shutting off - no restart within a few minutes. Dead Battery. There was no Battery Light on the dash to indicate a problem. I charged the battery, next day same thing. Battery tested good, and in fact I took it to Advanced Auto Parts and they said it was good.

I tested voltage with the motor running but no Charging even at higher rpm's. Curiously, no Battery Light on the dash. I took out the Alternator (a reman from RockAuto) and it tested good.

I grounded the D+ terminal from the plug and still no light. I checked as many grounds as I could find and everything seems OK. The wire in the harness does not appear to be broken and as far as I can feel around or find.

So it seems that my problem is either an ECM or the Instrument Cluster. Has anybody else had this happen? Is there any way to diagnose which one it is? Like anybody I don't want to spend hundreds of dollars just to find out it was the other part - or worse buy both and find out it was something else!

Thanks in advance

You can relax a bit, it is not the ECU, and the cluster won't need to be replaced. The warning light supplies a bit of current to get the alternator started. Without it, there will be no charging. Since the lamp does not light when you ground the D+ terminal, this points to a burned out bulb in the cluster or wiring between cluster and alternator. A continuity test from cluster to D+ connector will help narrow it down.

Paul

Thanks.

I do have continuity from the D+ terminal to the #12 pin on the green dash connector. I am guessing that localizes the problem to the Battery LED on the cluster.

Mine is a IJ0 920 900M and the closest part I have found on ebay is a IJ0 920 906. Will that work?

Okay, I was convinced that the problem was in the dash cluster so I bought the one on ebay. Woops, it's a 1.8 gas cluster.

Anyway, I went ahead and plugged it in. Still no battery light.

I am gonna go ahead and get a new Bosch Alternator. I am wondering if the problem is the Voltage Regulator after all even though the Auto parts guy says it's okay. I swore that the last time would be the LAST time to R/R the darn thing. I'll post back updates in case anybody is interested.

Symptom: Not Charging, No Battery light
-Battery Okay
-Alternator Checked OK
-D+ terminal has continuity to dash plug
-Grounds appear to be okay

How did this work out, what was the issue? I am having very similar symptoms.
Long time user of the forms, and first time post.

Cheers

I found a chaffed wire underneath the battery. It's the harness that comes off of the regulator and carries the trigger signal to the dash light. There's a plug in the harness right beneath the battery that apparently vibrates enough to cause the chaffing. Orange wire welded itself to the light blue one if I remember right.
Once I repaired that tiny wire, everything worked fine.
It was a major victory, as I had spent about 5 weeks late nights after work trying to diagnose it. Such a simple fix.

THANK YOU THANK YOU THANK YOU for this post. I've spent countless hours troubleshooting and replacing alternators that seemed as though they were faulty. Broken testers at advance auto and other tests that pointed all back to the alternator. It was a major victory to fix as well and my wife can now stop giving me crap about driving a 309K mile car.

Big Thanks for this thread. I had same issue, no charge and no battery light. I ran cluster test which confirmed that battery light doesn't light up. So I then started removing battery tray, btw. I think it may be possible to fix this issue without removing battery tray but there won't be as much room to play with the wires. Anyway, blue wire was completely cut and on orange insulation was ripped. Resoldered two wires with short piece of wire and put everything together. Started the car and it's getting 14.4V. thanks again for posting what was wrong and the fix.

Sent from my Nexus 6 using Tapatalk

Exact same issue, exact same fix

2003 VW Jetta TDI ALH. Car was charging/not charging intermittently. Replaced alternator, Auto parts store said ECM was possibly bad. All bull.
Found a broken blue wire in a group of 4, going into a plug under /left of the battery tray. Fixed blue wire and all is charging as intended. Will send pics if anyone needs
Thanks for posting, this saved the day, and the bank!

Not necessarily bull. I just had the same issue. No battery light and car just died. I changed my alternator today and it’s good. Also got rid of that horrible whine.
http://forums.tdiclub.com/showthread.php?t=488730

I believe the Bull that RedJetta is referring to relates to the FLAPS saying the ECU was the problem. He replaced the ALT and still had the same problem. His issue was not the same. In this case, it was the blue exciter wire as he explained and was thankful for this Thread for helping to diagnose the problem.

RedJettta said:

2003 VW Jetta TDI ALH. Car was charging/not charging intermittently. Replaced alternator, Auto parts store said ECM was possibly bad. All bull.
Found a broken blue wire in a group of 4, going into a plug under /left of the battery tray. Fixed blue wire and all is charging as intended. Will send pics if anyone needs
Thanks for posting, this saved the day, and the bank!

Click to expand...

Just edit your post and put in the pictures. It will help other people should the run across this thread. It's not going to be relevant in a couple years should someone need to msg you for the pics.

Same symptoms, different cause

Battery went dead, but recharged ok on a charger.
Checked the alternator voltage.
Nothing.
The charge light on the dash wasn't lit.
Pulled the battery box, and found the little plastic collar chafing a little on the brown ground wire, but not on the blue tickler wire.
Then I looked a little closer.
The m8x1.25 nut had fallen off the main alternator lead ....
I'm sure I'm the incompetent who didn't tighten it.
Bolted it back together, and it works fine.
Happiness is.

I have been chasing the same issue for a while now. The car is torn apart in my shop now. I will be checking this plug in the morning.

I am beyond lost at this point! I really thought when I found this post you guys had put me on the right path and I would find the smoking gun. The only test I have not done is the D+ to pin #12 on the dash plug. I have 12 volts on the blue wire when its running so I assume that means its ok? However I don't have a warning light. I am working off a Chilton's manual and in the charging system diagram they show a B1+ not a D+ on the alternator?
I have a new battery new alternator and I removed the alternator harness and tested each wire they all have continuity.
When I remove the alternator lead from the fuse on top of the battery it has 14.5 volts but will not produce more than 12.2 connected to the fuse. I have tested every fuse in the car.
I guess I need to test the #12 pin on the dash plug but I figured since the blue wire to the alternator has voltage when running that circuit is good?

Any insight would be GREATLY appreciated!
I have bee a member since 2012 and learned a lot here I just don't post much.

Is the alternator putting out 14.5 as measured with a multimeter at the bolt on the back of the alternator where the large battery wire connects? Car running.

Then only 12.2 after you connect it to the fuse block? If that is true your fuse block is probably melted, which is a common problem on these cars. Pull it apart and examine it, sometimes they are fixable, usually they need replacement.

Its producing proper 14v because there is no load. once you connect it, there is a load. try using jumper cables from the battery to another car. see if it still drops. my bet is that it will still drop back down to 12 because the alt is done for.
I had a similar issue,, i've had alts that stop charging at higher than idle RPM's from floating or depleted brushes to one that over or under volt due to bad internal regulators.
these cars do have a weak fuse block issue though. worth checking out but it would be totally melted (i have seen those) to make that much resistance to draw it down to 12v

Yes the alternator is putting out 14.5 volts at the back of the alternator. The voltage drop happens when it's connected to the fuse. The fuse is good there is no voltage drop across it something in the charging system is telling the alternator not to charge. Same symptoms as the original poster. I thought for sure I had this figured out when I saw this post but my harness is not damaged and I have 12v to the blue wire from pin #12 when it running. I don't know if this is coming from the gauge cluster to the alternator or the other way around. The one thing I know is I have seen the charging system warning light.
One other possible issue is that my glow plug warning light flashes all the time. I have read that this is usually caused by burnt out brake lights but the brake switch is good and both brake lights function correctly
I can't post pictures from my phone to this site and it doesn't seem to like tapatalk for some reason.

The Blue Wire is the exciter wire....

As TDIjarhead stated, it is highly likely the fuse block/panel on top of the battery is the culprit.

There is a long list of reasons the GP Light will flash. Brake lights being out is only one reason, must be both left and right out at the same time for it to flash, top center light makes no difference.

The fuse block on top of the battery all checks out. No voltage drop across any wires checking each side of the fuses.

Battery is new and tested good
Alternator is and tested good

nwbhoss said:

Alternator is and tested good

Click to expand...

Those are famous last words. Before I condemned the alternator, take the fuse block off and open it up. It's plastic with 2 halves. If that's fine the likely culprit is that tested ok alternator.

Problem solved!
The one thing I could not get out of my head was the fact I have never seen the battery light. I had to look online to find out where it was and what it looked like.
So today when I got home from work I unplugged alternator and and tested the blue wire voltage with the key on not running and it had 12 volts but no light. Next I grounded the blue wire and tada it came on! Now I am really scratching my head????? Why hasn't the light came on in the past? Why does it not come on when the key is first turned on with the rest of the indicators? So I plugged it back into the alternator and started it still 12.1 volts. The next thing I tried was connecting a jumper cable from the negative battery post to the alternator housing. The battery light came on!!!!!! I tested the voltage at idle and 13.7 volts! At 2000rpm it was 14.3!!! I don't even want to try to wrap my head around how it has run as long as it has this way. I have been through 3 batteries and 4 alternators in 60,000 miles approximately and never had that battery light turn on ever. I obviously will be going through every ground on this car and adding a few extra.
What a major pain this has been! Intermittent electrical gremlins are my archenemy. I hope that somebody else down the road will benefit from reading this and save themselves a headache. Thanks for the input and advice!

Here are a few of stories relating to grounding.

1. The ALH engine in my 84 Vanagon was hard to start from the get go........... I did almost everything in the book over almost two years as well as all the things suggested here in the Club......... shortening the story > bad grounding from the body to the transmission (ground strap there wasn't tight).

2. A friend of mine took his 1990 Vanagon to a shop to install a complete left rear tail light assembly. There is a major grounding point on the left side of the engine bay. The new light assembly over-taxed that rusty ground. The engine would not start. His Van stayed in that shop for months while they literally butchered it ,,,,,,,,,,,, why in the hell they got into the cluster is beyond me. As I said, ground issue at that major wiring point was the culprit. I cleaned up the mess over several days.

3. Due to a worn spot on the Pinion gear, I've not driven my TDI Vanagon very much in the last 18 months. So, to keep things going, I do start it occasionally. Well, back in January on a rather cold morning the battery acted weak but finally started the engine. Each start afterwards was worse until it would not longer start the engine. I would charge the battery and it would still struggle to fire-up the engine. So, I decided to buy a new battery but before doing so, I checked size (physical size too) by removing and it from the hole under the seat....... wow, I noticed the negative cable appeared slightly corroded (mostly white dusty looking stuff). I cleaned both cables ................ problem solved!

nwbhoss said:

Problem solved!

Click to expand...

I'm thinking the faulty ground has to be localized to the alternator or it's mounting. If it were a battery cable issue you should have had problems with the starter as well.

Well I finally found the smoking gun!
I started working on the grounds today. My plan was
A) find disassemble and clean every ground on this car
B ) Add a dedicated ground from a alternator mounting bolt to the battery negative
C) Add a dedicated ground from a alternator bolt to the chassis
Well started by removing the battery and battery tray to access the grounds there and when I tried to remove the main battery cable that goes from the battery to the block the stud it was bolted to was very angry. The threads were basically welded to the nut. It is obvious this has been hot a lot! Burnt black corroded and just ugly. I will be ordering a new battery cable and bolt with stud for it. I am glad I got to see what the problem was and now with it fixed and the extra stuff I am doing I won't have to worry about it happening again.
https://uploads.tapatalk-cdn.com/20210325/4aeca17b7bff0a8d4344386d7bc93a5d.jpg
https://uploads.tapatalk-cdn.com/20210325/38a6f87d8bab581b4903004ec74fd0f7.jpg
https://uploads.tapatalk-cdn.com/20210325/0551b4b7bf99d3912897421e9b37c6b8.jpg

I hope the pictures work, I agree with you noob_ti That's why I was not able to understand how it could be a ground, The starter is fine and no other systems showed any indication of a bad ground.
All the black on the cable lug and the mounting stud is not grease or oil. Its like baked on carbon or something the lug is pitted badly about half way through the material.