I've had a few people asking me how to rig up the voice control for use with the new firmware in the RNS510. I have a similar setup in my car, known as SDS, since I bought it and it works well. This is how I've done it myself (and this one is for Hedge's little passion wagon) - perhaps a little more complicated than required but, as ever, entirely reversible come sale time.
Parts you'll need (assuming you have the 26xx firmware, OEM Bluetooth installed and MFSW) -
Female Microphone Plug x1 1J0 973 332
Male Microphone Plug x1 1J0 973 119
Repair Wire x1 000 979 019 (for Plug 1J0 973 119)
Repair Wire x1 000 979 132 (for Plug 1J0 973 332)
Repair Wire x2 000 979 009 (for Plug 3B7 035 447 B)
Repair Wire x2 000 979 009 (for Plug 3B7 035 447 B)
2 - 3m of screened cable (minimum of 4 core), some heat shrink and soldering equipment.
Connections are as follows -
Plug 3B7 035 447 B
Pin 7 = Mic In +ve
Pin 1 = Mic In -ve
Pin 9 = Mic Out +ve
Pin 4 = Mic Out -ve
The idea is to remove the plug from the microphone in the headlining and plug in one end of this replacement lead which is then run down the door pillar, to the back of the head unit and connected to the Mic In connections in the existing green plug (3B7 035 447 B). From the Mic Out connections in the green plug and back up to the microphone but this time plugging in to the cable that runs to the Bluetooth Unit. I've soldered the connections and used heat shrink to tidy it up a little.
Here is the head unit end complete (i'll post up the other end when the plugs arrive)
Some pics of the microphone end
