When you remove the CD drive of this unit, it disables CD mode.I bought a 35€ CD CHANGER EMULATOR (only emulate) in order to input sound into the unit (using the AUX IN pins of the CDC harness)
For your project, If you use a PICO + 2DIN unit, I would suggest to put all in
I am actually working on my new project based on an AUDI CONCERT III + 1/2 DIN PROLOGY VGA USB touch screen. When you remove the CD DRIVE, it also disables CD mode. I am trying to emulate the MP3CD drive of the CONCERT II in order to have full integration beetween motherboard and the Audi unit use of the PREVIOUS/NEXT buttons, displaying MP3 name etc...)
http://coucouillu.free.fr/PROTO_CONC...ONCERT_III.zip (in french).