Communication For Initializing Impossible

When communication with DCM is impossible Detecting condition:

• Defective harness connector
• Power supply circuit malfunction
• Defective DCM
• Defective CAN communication circuit
• Defective Subaru Select Monitor

Trouble symptom: 

Communication is impossible between DCM and Subaru Select Monitor.

Wiring diagram: 

Telematics Refer to WIRING SYSTEM>TELEMATICS SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK FUSE. 
   1. Turn the ignition switch to OFF.
   2. Check the fuse of the DCM.

   Is the check result OK?

   Yes:  Go to  2.

   No:  Replace the fuse. If the replaced fuse blows out easily, repair the ground short circuit in harness between the fuse - DCM connector.

2. CHECK HARNESS (OPEN CIRCUIT). 
   1. Disconnect the DCM connector.
   2. Turn the ignition switch to ON.
   3. Using a tester, measure the voltage between DCM connector (harness side) and the chassis ground.

      Connector & terminal 

      (i270) No. 8 (+) - Chassis ground (-):

      (i270) No. 10 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  3.

   No:  Repair the open circuit in the wiring harness between fuse and DCM connector.

3. CHECK HARNESS (OPEN CIRCUIT). 
   1. Turn the ignition switch to OFF.
   2. Using a tester, measure the resistance between DCM connector (harness side) and the chassis ground.

      Connector & terminal 

      (i270) No. 14 - Chassis ground:

   Is the resistance 1 Ω or less?

   Yes:  Go to  4.

   No:  Repair the open circuit in the wiring harness between chassis ground and DCM connector.

4. CHECK LAN SYSTEM. 

   Inspect LAN system. Refer to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

   Is the check result OK?

   Yes:  Go to  5.

   No:  Perform the inspection according to the diagnosis for LAN system.

5. CHECK TELEMATICS. 

   Using the Subaru Select Monitor, communicate with the telematics system.

   Is communication possible?

   Yes:  The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.

   No:  Replace the DCM. Refer to ENTERTAINMENT & MONITORING>DATA COMMUNICATION MODULE .