E30 Zone

Iv taken my dash out for scuttle replacement
Everything seamed to go back well But behind the clocks there is a blue wire about 18 inches long with a black shroud with green caps either end with male fittings .
Now I know where it attaches rear of the clocks but for the life of me I can't remember where it went the other end a˜¡
Any help ??
Thanks Perry

Pics?

Plain blue wire is road speed signal, and plugs into a green socket frame clipped to the speedometer. The signal is present on all (or most) of the pins.
The other end should go to the cruise control, the radio for speed volume adjustment, or possibly some other accessory that needs a road speed signal.

So where abouts should it go ? Rear of the radio ?? Or where else