Topic: '04 Jaguar XJR D2B Fiber Optic

OK fellas.  I have a riddle for you.  I am in an '04 Jaguar XJR with the amplified Harmon Kardon system with navigation and an existing V60 phone system, all voice controlled.  I've successfully installed a CK3100 kit, which was no picnic.  Unfortunately, I have been unable to mute the audio system.  I can offer some details in an effort to get a correct response on how to proceed.  I'll make it worth your while.

On the Audio Unit, pin 7 of the CC8 connector (a blue wire) is labelled as phone mute.  Neither grounding nor applying a 12v signal to the line has done anything.  In studying the wire it reads no voltage until the in-car phone is in operation at which point the wire reads approximately 12v for the duration of the call.  Plan B was to cut the power to the Amp when on a call.  When pulling and replacing the fuse the Amp does not turn on again until the ingition key is removed and replaced.  Not a convenient solution.  Dang fiber optic information system I imagine. 

Plan C is to relay all the speakers invidiually.  Did I mention there are twelve of them.  This will work, but I'd be real happy to learn of a quicker, more straitforward solution.

So there it is.  I need your A game on this one.