Clio audio stalk

[sailingthewild]

I have just bought a secondhand Radiosat 6000 Radio/CD player for my daughters 1999 Renault Clio II car.
Although the Display Head shows the four display numbers for entering your code the audio stalk does appear to allow the codes to be entered as it should.
It could be the radio at fault or the wiring in between.

Does anyone have a cct diagram of how the stalk links into the radio?
Do the wires go direct or via a black box?
(I have looked in the Haynes manual (1998 - 2001) but it does not show this cct.
Any help would be appreciated as I'm getting my ear bend.