Added wireless Bluetooth audio to an Audi Concert II head unit (board revision 8E0035186D) without modifying the head unit itself. The idea was given to me by user @Shard7 on GitHub (Mark Patel) . The CDC commands were reverse engineered by him. Make sure to check his Github for an in-depth look at the project.

How it works

The Audi Concert II has a CD changer port on the Quadlock connector. By emulating a CDC (CD changer) device using an Arduino, the head unit can be tricked into accepting an external audio source through those pins. This allows me to change between FM Radio and CD (which is now Bluetooth). I followed the same pinout as Mark had posted in his diagram.

Parts used

  • Arduino Nano (CDC emulator sketch, copied from @Shard7 on github)
  • OKY3165 Bluetooth module
  • Quadlock connector
  • VAGCOM (Re-Writing the Concert 2 Flash to accept CDC input)

Result

Bluetooth audio with no visible modifications to the car interior. Sound is much cleaner than a cheap FM transmitter.