Checking Lead And Accessory USB Unit (AUU)

Checking fuses 

Check that the fuse for the function in question is intact.

Replace the fuse if it is damaged.

Checking the fault cause 

Check the fault cause as follows:

1. Ignition off.
2. Unplug the MOST-connector from Accessory USB unit (AUU).
3. Connect the MOST cable to special tool: 9512867
4. Ignition on.
5. Activate the infotainment system.
6. Check that the communication on the MOST-net works by reading out the status for the parameter MOST locked  for at least 30 seconds. The parameter indicates whether the MOST network is closed and communication possible. Click on the VCT2000 symbol to read out status on MOST-net.
7. If the parameter shows that the MOST network is not closed, check the receiving control module in the same way as described above.

The communication on the MOST network is working if the menu text is displayed. The cause of the fault is in the Accessory USB unit (AUU). Continue the fault-tracing by checking the component.

The communication on the MOST network is not working if the menu text is not displayed. The fault cause is then in the MOST cable for the next control module. Continue the fault-tracing by checking the fiber optic cable.

Checking the cable 

• Check the MOST connection. Check for dirt, loose connections and damage.
• Replace the MOST cable if no fault is found in the MOST terminal.

Checking the component 

• Check the audio module (AUD) power supply and ground connection for the Accessory USB unit (AUU).
• Check the MOST connection. Check for dirt, loose connections and damage.
• If no fault is found, replace the Accessory USB unit (AUU).

Remedy as necessary.

Other information 

• See: DOWNLOADING SOFTWARE AND REPLACING CONTROL MODULE (2009-2011)
• See: CHECKING THE SUPPLY VOLTAGE/GROUND TERMINAL
• See: SIGNAL DESCRIPTION
• See: FIBER OPTIC CABLE HARNESS, REPAIRING
• See: COMPONENT LOCATION, INFOTAINMENT (2005-2011)

• Continue 

  See: VERIFICATION