On a car stereo can anyone explain if the mute wire (for handsfree kits etc) requires a positive or negative signal from the device to activate it... Basically I am fitting a Parrot Bluetooth kit into an E46 BMW (52 plate) and have been told an ISO connector is not available for them. Instead I have been told I need to use a Nokia mute adaptor and splice into it... No problem really, it all plugged in ok, however the mute signal coming from the Parrot is negative when activated, but when I join it to what I think is the mute wire is the stereo cuts out abnormally.

Does anyone A: know the state the mute wire from the stereo should be in on idle and B: What the mute wire directly from the stereo is colour wise?

Cheers
Chris