Al,

>Piqued my interest.  Just what information
>does the VW stock 89 cruise control
>get and where does it get it.

>Motor speed via tachometer?
NO

>Driveshaft rotation?
NO

>How does it know how "fast" the venerable
>beast is going?
There is an inductive pick-up behind the
speedo. If you open the dash board cover,
on right side of the speedo back panel
you will find a small item screwed onto
the panel. Two wires are attached to it.
It takes the rotation of the magnetic
ring which regularly drives the speedo
pointer.

>I recently had a
>miserable experience with an alarm installer
>who botched a bunch of things on
>the van.  Tach no longer works, speedo cable
>ripped off the speedo, broken tab
>on the instrument cluster housing so the
>cover rattles etc etc.
>And of course the autopilot doesn't work now.
>So what should I check to see
>what other damage they've done re the cruise
>control.  It would help if I knew
>what signals the CC uses and from where
>they originate.
The CC uses the speedo pick-up, two switches
from clutch and brake paddle, and the control
stick switches as input. Output is three wired
to a vacuum pump in the engine compartment.

>Any help is of course appreciated.
On my experience, Audi is using exactly same
cruise control in Audi 5000.

Helmut
'80 Vanagaudi