Just for future reference as far as I have worked out it's not a relay, but the actual coupling transformer for the audio feed to the stereo from the hands free. I guess if this is not there then the audio in at the prewire plug under the glove box will not be connected, so you would have to intercept the ISO leads behind the stereo.
As the parrot kit claims it is good enough to be connected straight to the stereo in this way I guess the "relay" is just an element of protection included by vauxhall, however it's presence being essential to connect the prewire audio in to the stereo loom audio in.
My car already had it anyway
I fitted the parrot to the prewire loom without removing the centre console and without the autoleads adaptor. I had to use a multimeter and common sense to work out the prewire colours / pin assignments as all the pinout diagrams I found simply reference the pin numbers of the VDA and not wire colour.
An old 4 pin pentium 4 power connector fits the power socket on the parrot, soldered to the 12v, ignition indicator and 0v on the prewire loom (red, black and brown).
As for the mute and audio connector I had to use the included parrot ISO lead as it contains some sort of logic circuit to interface the mute signal (pull up or down I guess). So the mute wire from there soldered to the other black on the prewire loom, and the audio signal and ground to the twisted blue and brown wires with stripes (that feed the coupling transformer under the steering wheel).
I now get the stereo muted and 'PHONE' on the display, with audio routed through the stereo to the front speakers, volume controllable with the steering controls. All proper and everything.
Hope this is of help to someone in the future!
Phil
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Topic: Phone prewiring relay required? (Read 1864 times)