How do you find mute wire on car stereos? Is there special way to hook them up? I want to install Parrot 3200LCD on my 1999 Audi A4. Please help.
The easiest way is to purchase an integration harness for your car. Also Parrot uses ISO connectors to plug into factory radios for a very simple installation, unfortunately most cars sold in the USA do not. I think, however your Audi probably does use this connector. You will have to pull the radio to find out. Also the parrot handsfree kit has internal relays to lift the audio from the factory speakers (if you are not using the optional external speaker) This eliminates the need for a factory mute wire. Some Audi radios will have a mute wire because they were prewired for an old motorola analog cell phone.There is usually a sticker on the back of the radio showing a pin out of the wiring. if its there, connecting the yellow wire from the parrot kit will send a ground signal to this wire muting the radio. If you have the amplified bose system, I would suggest going the harness route for simplicity.
You can use a relay to kill the accessory power to the radio if your bluetooth kit has an external speaker. I've had to do this a few times.
If you use a automotive spdt relay
86-12v
85-(-)mute output from bluetooth
87a-radio accessory wire (radio side)
30-radio accessory wire(car side)
that will turn the radio off (like it would with the key) when the bluetooth is being used, and when its done the radio will come back on like normal without losing memory or anything.
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RTFM