Alternator question

[A Guy]

He group!
I just installed a new (rebuilt) alternatore as mine bit the biscuit the other night.  
When I started it the battery light came on and stayed on.  I have three wires connected to the alternator.  the main large pwr wire, a small red wire that's connect to a "male" on the side above the big red wire and a blue wire.  This blue wire was broken so I pigtailed a piece of copper wire in and connected it behind one of the 4 small primeter nuts.  The blue wire seems to be my culprit.  I got a V meter dropped of at the house today so I'll check that when I get home. Can anyone tell me what that blue wire does and where it's supposed to go?
Thanks

Greg

[fspGTD]

The blue wire, which is connected to voltage through the alternator warning light is the excitation circuit for the alternator.  It's needed to get the alternator "up and running".  Before the alternator is up and running, current flows and the warning light glows.  When the alternator gets up and running, it makes voltage at it's end of this circuit and the warning light turns off.

If you just grounded the blue wire to the alternator housing, your warning light would stay on all the time permanently and your alternator may never put out any current.

If you got the appropriate alternator for your application (designed to be used with a warning light, some are not and are referred to as "one-wire" alternators), there should be a terminal to hook the blue wire to.  This is not the same as the optional stator tap or "W" terminal found on some diesel alternators, used to provide a pulsating RPM signal to drive tachometer, upshift light, and RPM-dependent equipment.

[A Guy]

So if I understand, firstly it's not installed right.  Secondly, there should be a terminal (male) to plug into or a small threaded piece that I would slip a circular conector over and secure with a nut.  Correct?  I'll look again but I didn't see any other logical place.  I'll look at the old one again.  What do I do if there isn't a place to connect this blue wire?  Get a different alternator?  If this is the case what do I tell the guy at the parts counter?
Thanks
Greg

[fspGTD]

I don't recall which model VW you have, you didn't mention it in this post, and it's not listed in your signature, so I don't know what you've got.

But whatever it is, you should get a Bentley manual that is specific for your car if you don't already have one (they really are essential for working on VWs), and then consult the alternator removal and installation procedure under the electrical section.

[A Guy]

Of course.   :oops:   My bad.
'91, 1.6 N/A, 5 spd, 3 door, no air.  
I hear you on the Bently.  I have had no luck finding one in ottawa and area.  If someone in this area knows where I can aquire one of these I would be very thankful.  For now I have no Bentley and I must beg.

Greg

[fspGTD]

Ebay... or the classifieds section here or perhaps at VWVortex... or buy from a place that carries them and sells them new (IE: VW parts specialty repair places, VW parts dealers, Aftermarket VW performance parts sellers, etc)

Here's are a few I found on ebay.ca - this is the specific book you need:
http://cgi.ebay.ca/Bentley-VW-GTI-Golf-Jetta-Service-Repair-Manual-NEW_W0QQitemZ8021509391QQcategoryZ34234QQrdZ1QQcmdZViewItem

http://cgi.ebay.ca/Bentley-VW-Repair-Manual-GTI-Golf-Jetta-A2-MK2_W0QQitemZ8022737067QQcategoryZ34234QQrdZ1QQcmdZViewItem

http://cgi.ebay.ca/VW-GTI-Jetta-Golf-NEW-Bentley-Printed-Repair-Manual_W0QQitemZ8023117142QQcategoryZ34234QQrdZ1QQcmdZViewItem

[A Guy]

So the problem was that I was in a hurry and extremely tired.  I found the right spot for the blue wire.  This sloved the majority of the problems.  
When I start the car the red battery light is on untill a give it a little gas then it goes out.  Well, in sunlight it goes out.  In the dark it glows a little.  I beleive that I can get the belt a little tighter and this should solve everything.  I'll let you know when I can get under the car.
Happy New year everyone!  

Out.
Greg

[Wingaman]

Here is a version of the Bentley for Golf/Jetta 85-92 online.

But it might be usefull for reference for other model.

http://ep0niks.ctech.ca/vw/eva2/index.html

[zyewdall]

Sounds like you figured it out.  The other way, if you've got the Bosch alternator at least, is to put a jumper from the fuel cutoff solenoid on the IP to the exitiation terminal just below the two wide ones for the main power at the alternator.  Put a 50 ohm 2 watt resistor in this jumper, or it'll backfeed the IP solenoid and the engine won't turn off.  This essentially works the same as the alternator light, but still works when the alternator light bulb burns out.  I did that on mine and it works great.

http://www.vwdiesel.net/phpBB/viewtopic.php?t=1612&highlight=

[A Guy]

Well I figured out how to tighten the belt on the alternator thinking that that would solve my light issue but nope.  When I start the car cold  the Battery light is on bright until I give the accelarator a push then it fades but is still on.  All wires are connected.  Anyonbe have a thought or two.  Could my rebuilt alternator be no good?  I'll put the volt meter on again tonight and let you know tomorrow.  
Thanks all.
Out!
Greg

[zyewdall]

See what the voltmeter says, but it sounds like you have the same problem the thread I referred to above was discussing -- if it's not getting good excitation current, it won't charge till you rev it.

Z

[A Guy]

I read the link and it seems to be the same thing but my light works.   You're saying that If I install a jumper wire the alt will charge the battery without blipping the throttle.  I'm not sure what you mean by "IP" but I'll see if that online bentley link has any info as I still don't have a manual.  
I'll do the Volt metter tonight.  Too much snow last night to bother.  
Out.

Greg

[zyewdall]

... I'm not sure what you mean by "IP" ....

Injection Pump

[A Guy]

Appologies for the delay.  
I noticed that the 16 gauge(approx) red wire w/black strip that is wrapped with the large red wire (main on alternator) broke in a different spot.  I had some time once I got to the store this morning and traced it back to a plug that goes to the starter.  I got a spool of new wire and I'll see if I can cut it close to the plug and run new wire to the female plug on the alternator and see if that fixes it.  
Out.
Greg

[A Guy]

Well after a couple of weeks of dealing with the every changing Volt light. I canged the wires to no avail.  Then one night last week my fiance and I were heading home after long day in the city when all of a sudden I started hearing a chattering sound that eventually really got my attention with a loud ping and the little red light got really red and the entire engine lurched.  Long story short the screws around the housing of the alternator backed out into the turbine.  This alternator was ovbviously rebuilt at 3:00pm on a Friday.  Swapped it this morning in the parking lot of the store where I exchanged it.  Fired up no more red light.  These perimeter screws all have nuts on them .  
I'm soaked but the problem is fixed!!!!!!!!!!!!!
Out.
Greg