Diagnostic Procedure For Subaru Select Monitor Communication: Inspection

Trouble symptom: 

Cannot communicate with [Body Control].

Detecting condition: 

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

Wiring diagram: 

CAN communication system Ref. to WIRING SYSTEM>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK POWER SUPPLY CIRCUIT  .

   Connect DST-i to data link connector.

   Does DST-i turn ON?

   Yes:  Go to  4 .

   No:  Go to  2 .

2. CHECK POWER SUPPLY CIRCUIT  .
   1. Turn the ignition switch to ON.
   2. Using the tester, measure the voltage between data link connector and chassis ground.

      Connector and terminal 

      (i221) No. 8 (+) - Chassis ground (-):

      (i221) No. 16 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  3 .

   No:  Repair the power supply circuit.

   NOTE: In this case, repair the following item:

   • Open or ground short circuit of harness between battery and data link connector
   • Blown out of fuse (M/B No. 2, F/B fuse No. 3)
3. CHECK HARNESS BETWEEN DATA LINK CONNECTOR AND CHASSIS GROUND (OPEN)  .
   1. Turn the ignition switch to OFF.
   2. Using the tester, measure the resistance between data link connector and chassis ground.

      Connector and terminal 

      (i221) No. 4 - Chassis ground:

      (i221) No. 5 - Chassis ground:

   Is the resistance less than 5 Ω?

   Yes:  Check for poor contact of the data link connector, and repair a fault, if any. When no fault is found, Go to  4 .

   No:  Repair the harness and connector.

4. CHECK SUBARU SELECT MONITOR  .
   1. Connect the Subaru Select Monitor to a normal vehicle.
   2. Start the engine and establish communication between the Subaru Select Monitor and vehicle.

   Is communication possible?

   Yes:  Go to  5 .

   No:  Use another Subaru Select Monitor because the CAN communication circuit of the Subaru Select Monitor is faulty.

5. CHECK LAN SYSTEM  .

   Perform the diagnosis for LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

   Is the check result OK?

   Yes:  Go to  6 .

   No:  Perform the diagnosis for LAN system.

6. CHECK CONNECTOR  .

   Check poor contact of body integrated unit connector, data link connector and coupling connector.

   Is the check result OK?

   Yes:  Go to  7 .

   No:  Repair the connector.

7. CHECK FUSE  .
   1. Turn the ignition switch to OFF.
   2. Remove a fuse from the fuse box.
   3. Check the fuse.

   Is the check result OK?

   Yes:  Go to  8 .

   No:  Replace the fuse. If the replaced fuse blows out easily, repair the ground short circuit in the harness between the body integrated unit and fuse.

8. CHECK BODY INTEGRATED UNIT CONNECTOR POWER SUPPLY CIRCUIT (OPEN)  .
   1. Disconnect the body integrated unit connector.
   2. Turn the ignition switch to ON.
   3. Measure the voltage between body integrated unit connector and chassis ground.

      Connector and terminal 

      (B73) No. 7 (+) - Chassis ground (-):

      (B71) No. 1 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  9 .

   No:  Check the harness for open or short circuit between body integrated unit and fuse.

9. CHECK BODY INTEGRATED UNIT GROUND CIRCUIT (OPEN CIRCUIT)  .

   Measure the resistance in harness between body integrated unit connector and chassis ground.

   Connector and terminal 

   (i81) No. 4 - Chassis ground:

   (B72) No. 1 - Chassis ground:

   Is the resistance less than 5 Ω?

   Yes:  Check the connection between the data link connector and Subaru Select Monitor.

   No:  Repair the harness for ground line.