12-Pin Connector 4, Cd Changer -R41- /External Audio Source Connection -R199- /Multimedia System Control Module -J650-

Fig 1: Identifying 12-Pin Connector 3 For Telephone And Microphone Signals

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

1. Left audio input (+) to External audio source connection/Multimedia system control module 
2. Audio input ground External audio source connection/Multimedia system control module 
3. Audio ground from the CD changer 
4. Terminal 30 to the CD changer 
5. Not assigned 
6. DATA OUT to CD changer 
7. Right audio input (+) External audio source connection/Multimedia system control module 
8. Left audio from the CD changer 
9. Right audio from the CD changer 
10. Control signal to the CD changer 
11. DATA IN from the CD changer 
12. CLOCK from the CD changer