Add "W" terminal wire to Bosch/Valeo serp-belt TDI alternator

[Syncroincity]

I have a nice fat 120 amp alternator out of a TDI attached to my AAZ install, the problem was; no W terminal to run the tach. I used a MKII "2.22" diesel tach fitted into my original Vanagon instrument cluster. I used this alternator to provide; 1. Clutched over-run pulley to take the strain off the AAZ crank nose with the serpentine setup, and 2. AMPS, baby.

Plastic cover and easily detachable brush pack... remove a few screws and you're looking at the stator windings. Check your brush condition while you're in here.

Photos are representative; not my alternator.






On these alts, the winding wires terminate in these little loops that mechanically crimp and lock them in. The outermost ones are what you need, one that does not connect to a diode. Red arrows in the pic below. (You can see the diodes below the other connections, round, fairly obvious.)  Find one with a little space between the winding wires, or use a screwdriver blade to spread one open a bit. Clean with a wire brush to expose good bare metal, and loop a wire end into it and re-crimp the winding ends. Solder the wire. I had to use a butane torch, my soldering iron wouldn't quite heat everything up enough.




In the Vanagon, connect that wire to the solid blue wire in your junction box if present.


Result: tachometer reading! I have no way to verify the RPMs, but it seems close to where it should be, a bit high maybe... shows about 900 at idle. The serpentine pulley is slightly smaller than the v-belt pulley. I'll have to go in and find the adjustment pot on the tach one of these days.

[theman53]

good deal. It just picks up off one of the stator wires for the w signal then?

[GEE-BEE]

I found a local shop that has new and ohc units with the W terminal

They offer powdercoated housings also for 45.00 in any color

I have a 90 and 120 amp core

GB

[vanbcguy]

There is an AAZ 120A alternator with a W terminal in the wild... I put one on my build. :-D  But this is great for anyone that has a non-W alternator already!

Sent from my HTC One XL using Tapatalk

[Syncroincity]

good deal. It just picks up off one of the stator wires for the w signal then?

Exactly, and it doesn't matter which one you pick (there are six, 3 pairs), as long as you tap it before the diodes.

I'd seen a few how-to threads about this but all were kind of vague about wire placement, and most concerned the older style alternators.

[Syncroincity]

They offer powdercoated housings also for 45.00 in any color

This would be nice... All my AL components look like absolute crap.

[rodpaslow]

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[rodpaslow]

[rodpaslow]

I added this picture as I have an older 1Z/AHU alternator with the back plastic off and I removed brushes as I will likely replace them.  I cannot tell with this one if a set (these stand upright towards the camera) is connecting to the diode.  Is there a trick to telling what does and what does not?

[rodpaslow]

Are the center ones part of the diodes?  Can a person use a ohm meter to test connectivity to them?

I saw on another site (4 x4 of some kind) had a picture quite similar and connected a wire to one of the six and his worked.  I'm assuming like the one above it matters which of the six.  do I need to take it apart further to see which are which?

[rodpaslow]

If you go from the top clockwise I tried the 4th one.  No dice, did not have the signal or check with mutimeter.  This post has a different alternator to start with, but I see the end posts both are useable.  I'm going to try one of the end ones next.  Pulled the alternator apart, nothing inside helps to determine which post will work.

[vanbcguy]

There are quite a lot of usable alternators that do have the 'W' terminal for what it's worth.  I have a 120A serpentine one.  For some reason a lot of the ABA motors have an alternator that came with a 'W' terminal, so there are loads of them available.

[rodpaslow]

vanbcguy, I have a ABA unit (that's what the car originally had in it) serp.  I haven't even looked at it thinking it would not be worth even trying it assuming the mounting would be different and no W.  Let me have a look at it later today as it is from an Can ABA motor.  If it doesn't have a W I will certainly buy the one you have - maybe pm me price just in case.

[vanbcguy]

Hey sorry, I meant I have one on my car, not that I have one for sale...

Part number is AL0184X - I bought mine from FCP Euro

http://www.fcpeuro.com/products/volkswagen-alternator-cabrio-corrado-eurovan-golf-jetta-passat-transporter-al0184x

The 'W' terminal is on the 2-pin connector on the end of the alternator. 

[GEE-BEE]

Same one I used on my White alternator

GB