http://www.nexxia.co.uk/car_stereo_fitting_kits/Audi/A3.htm
PC9-404 £10.75
Instal guide here too
http://www.nexxia.co.uk/Installation_Advice/Audi_Harness_adaptors.htm
When installing Car Stereo Fitting Kits for Non-Bose systems, using PC9-401, PC9-408 or PC9-409, the lead needs to be adapted to allow switching on of the original fitted Amplifier.
All Audi's using these leads have active rear speakers, built into the speaker themselves. These adaptors convert the New head unit Speaker level output to line level output for the active speakers. These leads feed into the Red Mini ISO plug.
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The blue & White wire on the Red mini ISO plug also needs to be connected to the Blue wire coming off of the New Head Unit (marked Amp Remote). At the same time the blue wire on the PC5-90 adaptor also needs connecting to the Blue wire off the New Head Unit.[/FONT]
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To do this cut the blue wire between the two Black ISO connectors half way along. Plug the blue & white lead supplied with the red crimp connector on the end into the bullet connector from the Red Mini ISO plug.[/FONT]
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Cut the blue wire from the PC5-90 half way along. After stripping, feed both the blue from the PC5-90, and the blue coming from black ISO connector which will plug into the New head unit (not the car end) into the Red Crimp connector. Crimp the connector using proper crimping tool.[/FONT]
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Once complete both the PC5-90 and Red & White wire on the mini ISO connector should be getting +12V from the new head unit.[/FONT]
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This will power the antenna adaptor and also signal the remote amplifier to switch on.[/FONT]
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Also note if your new head unit has RCA outputs with an output above 2.2v, you could use PC9-404 or PC9-410. Installation is the same as above accept the RCA connectors replace the speaker connectors.
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