Test A: No Communication With The Audio Unit - Except Navigation

PINPOINT TEST A: NO COMMUNICATION WITH THE AUDIO UNIT - EXCEPT NAVIGATION

A1-A2:

A2-A4:

Normal Operation
The audio unit communicates with the diagnostic tool on the standard corporate protocol (SCP) network through circuits 914 (TN/OG) and 915 (PK/LB). The audio unit receives voltage at all times through circuit 1772 (VT), voltage in RUN/ACC through circuit 1499 (PK/LG), and ground through circuit 694 (BK/LG).

Possible Causes
- Fuse
- Circuit 694 (BK/LG) open
- Circuit 720 (RD/YE) open
- Circuit 1499 (PK/LG) open
- Circuit 1772 (VT) open
- Central junction box (CJB)
- Audio unit