Data Bus On Board Diagnostic Interface Connector

20-pin connector, black 

Fig 1: Data Bus On Board Diagnostic Interface, Multi-Pin Connector Assignments

Courtesy of AUDI OF AMERICA, LLC

1. Battery + (terminal 30)
2. Battery + (terminal 30)
3. Reserved for external diagnosis
4. Reserved for K-lead
5. Comfort CAN bus Low
6. Powertrain CAN bus Low
7. Reserved for shielding
8. CAN Bus instrument cluster Low
9. Diagnostic CAN bus Low
10. CAN-Bus Infotainment Low
11. ground - (terminal 31)
12. ground - (terminal 31)
13. Instrument cluster prompt input
14. Terminal 15
15. Comfort CAN bus high
16. Power CAN bus high
17. Reserved for shielding
18. CAN Bus instrument cluster High
19. Diagnostic CAN bus High
20. CAN-Bus Infotainment High