Speedometer adapter with electric wire?

Is anyone familiar with a TH400 speedometer drive adapter that has an electric wire coming off of it? Checking with a test light, it seems to be just a ground -- but I'm wondering what this is supposed to do?

See the pic...

Thanks for any guidance!

Karl Koenigstein
BFGoodrich Racing

 

Karl,
Where in the hell did you get that speedo housing? In all the years of yarding, I have never ever seen that. Sheesh, you got me stumped ....ole buddy! ou:

 

Karl,

I'm not an expert transmission mechanic but might that connection be from a vehicle that came with a transmission temp gauge?

Dean

 

I have a little more information about how this thing acts -- it's a governor of some sort. At stop and low speed, the electric wire has continuity with the housing -- so the electric wire is grounded. Above a certain speed, the mechanism inside throws weights out, and breaks the connection -- so it's not a ground anymore. Does that ring any bells for anyone? Emission control circuit that is speed dependent? Minimum speed for cruise control (woulda thought that was all in the black box for the cruise)?

Thanks
Karl Koenigstein
BFGoodrich Racing

 

is that something to do with the "max-trac" option?
what year is the car?

 

Max Trac

You just never stop learning about Buicks - good one Yuk/Larry ! ou: :TU:

 

That's kind of neat, and shows how there isn't really anything "new."