Autoleads PC9-132

[mickywillis]

Hi, is anyone familiar with this Autolead SmartLead and Stalk adapter?
Its used for connecting Sony HU's to the R75/ZT models and also LR Discovery from 04/2001 on.
I have a Symphony system in the car at this time and want to change it for my Sony unit. The Symphony connectors are the same as the Sony one, so no need to change the wiring there. What I do need to do is use the PC9-132 Stalk adapter function to control the Sonys' HU via the steering wheel controls.
The ISO connector terminates into a 17 pin connector (BMW?) and the flyleads from the stalk adapter are also terminated onto here.
Can anyone tell me what the 4 leads from the black box are for? I think the red lead is a +ve feed (connected to Yellow wire on ISO connector), the grey a -ve earth lead (connected to Black on ISO connector), but what are the black and blue wires? Are they the switching wires that need to be fitted to the power supply plug in terminals 2 and 3 to control the HU from steering wheel controls
Please see attached photos

[biggles]

Pin 2 and 3 on the Symphony ISO is definitely the steering wheel leads, pin 8 is ground, pin 7 is ignition switched +12 and pin 4 is permanent +12V.