You have a hall effect sender in your distributor.  I would say it is
looking for an input from your green wire on your coil.  But that sounds
more like a tach signal to me (rpms).  Hope this helps,
Ken Wilford
John 3:16
www.vanagain.com

Mark Thoma wrote:
> Hey everyone,
> Putting an aftermarket VDO speedo in my van and it requires a "Hall Effect Sender" input.  What the???? The van is an '87 with the two part speedo cable that joins at a box.  Ideas?
> Mark
> p.s. thanks in advance.
>
>