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Discussion Starter #1 (Edited)
Hi everyone,

Last August I had a 2003 GLS 1.8T B5.5 wagon with ~146,000 miles fall into my lap for a song. It ran just fine, but the original owner wasn't much for maintenance (among other things, he'd never done the timing belt). So needless to say, I've had this car in pieces in my garage until very recently... (I figured while the front end was off, I'd do a few other things too):
- timing belt, tensioners, pulleys, drive belts, water pump, thermostat, new coolant, etc
- replaced stock 90A Valeo alternator with Bosch "rebuilt" 120A Valeo unit, replaced battery with a slightly used (~1 year old) batt out of a friend's Passat (he had a parts car)
- valve cover gasket, new plugs
- replaced the stock headlights with aftermarket HID headlights, replaced cracked/pitted foglights with used OEM equipment
- replaced cloth interior with a leather interior

etc etc.

The car is now back together, and looks great, and drives great! Here's a "glamor shot" just for kicks:



The problems I'm having are as follows:


1) Since I first started the car up after it had been sitting, I've been seeing a battery indicator light. The batt was low, so this didn't concern me too much. After running it a few times (bleeding coolant, etc) I'm also now seeing the warning "ALTERNATOR WORKSHOP", and I can definitely say that after driving around for a bit - the batt is not getting charged (almost killed it, but got successfully home and hooked back up to a battery charger I recently acquired).

I've been doing a lot of poking around on the innernets about this, and from what I can tell there it sounds like there is a fusible link between the alternator and the battery. My guess is - since my car was equipped for the 90A, and I upgraded to the 120A, I've probably blown the fuse. Many manuals and pics I've found indicate this is the "S177" fuse, and even show pictures of a "box on top of the battery", like this one (not my car, found this on the innernets):



But from what I can tell, that's a Jetta, or a Golf, and there's certainly no "box on top of the battery" on my car... In fact, I can't seem to find anything similar on my car anywhere. My hope is that one of you can tell me if I'm headed down the correct path - and if possible, just where this is located


2) This is the problem where I may very well prove myself an idiot. As noted above, I changed out the entire interior (cloth to leather). Right around the time I started the engine for the first time (to test that everything was back together correctly before reassembly of the front end), every last interior piece (read: seats) was out of the car. I've been seeing an "AIRBAG FAULT" warning ever since, even after reinstalling the seats. My understanding now is that the airbag sensors are plugged into the seats, and by starting the car with the seats out, I've effectively shot myself in the foot. How screwed am I here - do I need to pay the dealer gobs of money to reset this now? I've even heard that they won't do this job for legal reasons.. Anyone been down this path before that can offer advice?

Thanks very much in advance! I'm a new member, but have been poking around the site for a little while now, and it's truly a great resource.

Cheers,
-Dan
 

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Normally there is no fuse in the starting or charging circuits. The alternator is likely faulty.

With the engine running, what is the voltage between ground and the positive battery post ?
With the engine running, what is the voltage between ground and the large terminal on the alternator ?
With the engine running, what is the voltage between ground and the small terminal on the alternator ?
 

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2004 B5.5 Variant 1.8T
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The airbag light just needs to be cleared with vagcom. I know of a few members in your area that may have Vagcom.

Also, make sure the little plug on the back of the alternator is properly cleaned and seated.
 

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Don't discount the possibility that the charging cable is corroded and bad. More than half of all VW's I've owned have had this problem. Check by measuring voltage drop across the cable.
 

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The airbag light just needs to be cleared with vagcom. I know of a few members in your area that may have Vagcom.

Also, make sure the little plug on the back of the alternator is properly cleaned and seated.
You can clear the airbag light using the free VCDS version and a cable off ebay if you can't find someone with a VAG COM.
 

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That photo look like the top of my old GTI battery. I had the exact same issue.
 

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Like said before, my guess is that you have a bad alternator (or bad connections to it). Airbag can be reset by the dealer ($$) or by anyone with VCDS cable. See if you (or VAGguy can help you) can locate someone in ur area.
 

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Discussion Starter #8
Thanks very much for the responses everyone! Greatly appreciated! I'll check the alternator connections and voltages tonight after work and report back.

Assuming the new alternator is indeed faulty (an ironic proposition given I replaced what seemed to be a perfectly functional unit with a new one to avoid this very problem), is the easiest/fastest way to swap it out to remove the front end again? Looks pretty tight space to pull that fan clutch assembly out...

Cheers,
-Dan
 

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It is not uncommon to get a faulty Re-man Alternator.


I got a 409.1 VAG cable from Amazon or eBay, the disc that came with it had viruses, I did not use it.
VCDS Lite unregistered will scan all modules one by one, but it needs to be registered ($99) to run TBA, all modules in one scan, and some other operations.

This is how I set up my VCDS Lite, I later registered it.
1 - Get 409.1 VAG cable (About US $10)
2 - Download VCDS Lite and install in Windows. Ross-Tech: Home
3 - Download USB-Com Port driver and install in Windows. FTDI Drivers
4 - In Windows device manager; set the Com Port to Port 4
5 - In VCDS Lite, set the Com Port to Port 4
6 - Connect cable to PC and OBD port, switch on the Ignition and test the port.
7 - Select engine and scan
Note: If you only have a Mac, you can run VCDS in a Windows virtual machine.


Note: VAG Com is Ross Tech's old version of VCDS, they changed the name years ago.
 

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It would make a big difference if this is a Bosch "quality remanufactured" alternator or "Bosch remanufactured" (meaning remanufactured by Bosch). The second one is as good as a new Bosch alternator IMO.
 

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...
Assuming the new alternator is indeed faulty (an ironic proposition given I replaced what seemed to be a perfectly functional unit with a new one to avoid this very problem), is the easiest/fastest way to swap it out to remove the front end again? Looks pretty tight space to pull that fan clutch assembly out...

Cheers,
-Dan
Last year I had to pull the alternator on my B5 Passat 1.8T wagon to change the thermostat. (I was flushing the cooling system after replacing an internally leaking oil cooler.) I did not have to pull the lock carrier out to service position. (Been there ... done that a year earlier for timing belt and water pump. Next time I would be inclined to do thermostat and coolant flush at the same time, although this is not as urgent as on the 30-valve V6 engines, with the thermostat buried under the timing belt.)
 

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Discussion Starter #13
Hey everyone,

Bad news / good news:

1) Bad news is, I finally managed to do some testing on that alternator, and my findings pretty firmly confirm your suspicions that my brand-new alternator is bad:

First, I tested the battery with the engine off: 12.32
alternator big post to ground with engine off: 12.30
alternator small post to ground with engine off: 0

alternator big post with engine running: 11.93
battery with engine running: 11.83
alternator small post with engine running: 10.6


2) Good news is, I know a European vehicle mechanic (who is actually doing the suspension on my E350 4matic wagon as we speak). They said if I brought the Passat by after it was running again, they could clear my airbag fault no problem.


So, I guess I'm going to rip the front end back off of this thing, and replace the alternator.. again... Sigh. Thanks for your help everyone! I'll let you know how things turn out...
 

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Discussion Starter #14
BTW, this is the alternator I ordered (and which is apparently bad):
https://www.fcpeuro.com/products/audi-vw-alternator-a4-a4-quattro-passat-al9404x

So now the question is:
- Do I have them send me another 120A?
- Do I just use the existing 90A that came with the car? (Has about ~146,000 miles on it)
- Do I have them send me a 90A instead?
- Do I procure another alternator from another source?

Am I overthinking this at this point? Certainly possible. Ugh.
 

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the 120A upgrade is a good idea. I've bought two Bosch remanufactured alternators from FCP with no problems. I'd call them and tell them of the findings you posted above; then, ask them how they want to handle it and then tactfully suggest you expect them to make good on the alternator.
 

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This is supposed to be a good alternator. Like Jay said, call FCP and talk to them. 120A in better than the 90A that came with the car, assuming is in good working condition.
 

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Just kind of typing out loud. If it were another company, they might ding you for using an alternator not specd for the car. I wonder, would anyone know if both versions spin at the same rpm relative to the engine rpm for either 1.8 or 2.8?
 

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I would expect the size of the pulley would be the same between the 90A and 120A (otherwise you'd need a different accessory belt), so, the spin rate would be the same. The difference would be in the windings and the rectifier.
 

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E34, it appears that ordering the correct alternator depends on what came in your car. 2003 catalog shows 4 different alternators. 90 or 120 A , Valeo or Bosch. 4 possible alternators, they all could be Bosch reman but the part number is different! AL 9404 is the correct alternator if you have an original Bosch alternator system. For Valeo system the 120 A Bosch is AL 0803. X just means it's remanufactured (in general).
Someone with more alternator experience might chime in, but I think you need to order the correct alternator?!

Talk to FCP, they usually know their stuff.
 

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Well, I'll be a dissenting voice and say that 120A is only an upgrade if you are doing something that really requires it. A higher power rating won't magically increase durability on a normal stock car that came with the 90A, as the 90A isn't undersized on cars that came with it. While I wouldn't turn down a 120A unit as a replacement for a 90A, I'd never pay extra for one either.

Having a local auto electric shop rebuild your 90 will be MUCH better than any reasonably priced rebuilt 120 from a parts outlet.
 
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