MFA and cruise together - speed sensor wiring

[treed2 at u.washington.edu (T. Reed)]

I can't seem to find anything too helpful about how to wire up both the
mfa and the cruise control to the speed sensor. If you folks know
-anything- about how to do this I'd really appreciate hearing about it.

The best I came up with was the pin on my instrument cluster that is
labeled "Hall-Geber" (I assume that means Hall Sender) on the flexible
circuit board and if you trace the wire it -does- end up at one of the
three pins on the speed sensor. I can't imagine why the speed sensor
signal would go beyond the instrument cluster other than for cruise
control, or maybe a radio with speed-based automatic volume control. Or
motronic... but this cluster is from an 86 golf 8v. VW didn't use motronic
until well after 86, right?

I checked the wiring harness in the car and there is no wire it in
corresponding to the "hall geber" pin.

I hooked it up an oscilloscope to that wire and the cluster ground and all
I could get was a couple millivolts (like.. 5 mV or so) of increase from
the baseline noise (which I was never really able to get rid of) when I
spun the speedo drive quickly by hand. The way I see it, that could very
well just be coupling/crosstalk between wires on the cluster.

With that kind of minimal result, I'm hesitant to "just hook it up" and
risk frying my instrument cluster and/or cruise control computer. It seems
to me like the output should be on the order of volts or at least tenths
of a volt.

The other thing is.. the "troubleshooting cruise control" section of the
bentley specs the resistance across the 2 speed sensor wires as 90-110
ohms. But between any of the 3 wires on the speed sensor I have it is an
open circuit.

I've searched Google Groups and vwvortex and read hundreds of messages.. I
can't think of anywhere else to look.

-Any- help would be appreciated!

Thanks
-Toby