Paul, the 'W' pin is for the tachometer signal, as you suspect. No current
should be applied to this terminal. Motorola alternators, in my experience,
have all been of poor performance and reliability. I would recommend having
the alternator checked by a reputable alternator/starter repair shop, and /
or replace it with a new Bosch unit.

Karl

----- Original Message -----
From: Paul A. Cianciolo <paulc@SNET.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, September 18, 1999 10:03 AM
Subject: "W" pin on alternator? What for?

> Hello Folks,
> Finishing up the 1.9TD in my Vanagon..  Actually got to drive a mile or so
> today.  Man !! you can really fell when the turbo kicks in
>
> Lots more work to do yet.  I am not charging properly at this time.  There
> is a "W" pin at the back of the Motorola 50 amp alternator.
> With the Alt. connected tot eh battery properly, the alt will not charge
the
> battery.  How ever if I apply battery voltage to the "W" pin for 1 second
> or so the alt. will charge ok.
>
> I ihave heard that this pin is used for a tachometer input in the Diesel
> cars. Is this so or does it need to get a quick pulse of battery voltage
to
> turn on the regulator circuit in the alt.
>
> Bentley is of no help... I also checked some of my earlier Rabbit books
>
> Thank you
>
>
> Paulc
> W1VLF
> Cloudbounce Webpage  http://www.qsl.net/w1vlf/
>
> 1986 Vanagon Gas
> 1982 Vanagon Diesel  Soon to be Turbo Diesel 1.9