Here is the stereo radio wiring information for your 2003 Audi B6 A4 with the standard, symphony, or Bose systems. It will be useful when installing an aftermarket radio, sound stereo system, or other automotive accessories. Make sure to grab the appropriate tools to test all the wires in your A4. Please check it over and use it as a GUIDE to help you locate the appropriate wires. This schematic is provided free of charge and may not be 100% accurate. Failure to properly test all the wires may lead to vehicle or bodily damage. All information is provided as-is and accuracy is not guaranteed.
If you find any conflicting info please leave a comment with what you found in your Audi B6 A4. If you don’t see the wiring diagram you need comment and we will try to add it ASAP. Thanks for looking!
Keep in mind if you are installing a new radio you may need the radio removal keys, the wiring harness, the antenna adapter, and the mounting kit as well. See the links below to purchase these items.
2003 Audi A4 Car Audio Stereo Radio Wiring Diagram Schematic Colors
Car Radio Constant 12v+ Wire: Red/Blue
Car Stereo Ground Wire: Brown
Car Radio Ignition Switched Wire: Not available Grab @ Fusebox
Car Stereo Dimmer Wire: Gray/Blue @ Radio with Nav Only or Cigarette Lighter
Car Radio Illumination Wire: Gray/Blue @ Radio with Nav Only or Cigarette Lighter
Car Stereo Power Antenna: N/A
Car Radio Amp Turn On Wire: White @ Radio Pin 6 in 20 Pin Plug
Left Front Speaker Wire (+) Positive: Brown/Green
Left Front Speaker Wire (-) Negative: Blue/Yellow
Right Front Speaker Wire (+) Positive: Brown/Blue
Right Front Speaker Wire (-) Negative: Green/Blue
Left Rear Speaker Wire (+) Positive: Brown/Yellow
Left Rear Speaker Wire (-) Negative: Red/Yellow
Right Rear Speaker Wire (+) Positive: Brown/Black
Right Rear Speaker Wire (-) Negative: Red/Green
Center Channel Speaker Wire Positive / Negative: Tied in with front speakers.
Subwoofer Speaker Wire Positive / Negative: Red/Gray Brown/Gray @ Amp
Front Speaker Size: N/A
Rear Speaker Size: N/A
Amp Amplifier Location: Passenger side of trunk behind carpet
Radio Removal: VW / AUDI / MERCEDES Keys