Diagnostic Procedure For Subaru Select Monitor Communication: Inspection

Trouble symptom: 

Cannot communicate with [Air Conditioner].

Detecting condition: 

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

Wiring diagram: 

• Air conditioning system Ref. to WIRING SYSTEM>AIR CONDITIONING SYSTEM>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 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 perform 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  .

   Check the LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

   Is the check result OK?

   Yes:  Go to  6 .

   No:  Repair it according to the diagnosis for LAN system.

6. CHECK CONNECTOR  .

   Check poor contact of A/C control module connector and data link 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 harness between the A/C control module and fuse.

8. CHECK A/C CONTROL MODULE POWER SUPPLY CIRCUIT (OPEN)  .
   1. Disconnect the A/C control module connector.
   2. Turn the ignition switch to ON.
   3. Measure the voltage between A/C control module connector and chassis ground.

      Connector and terminal 

      (i107) No. 1 (+) - Chassis ground (-):

      (i107) No. 8 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  9 .

   No:  Check for open or short circuit in the harness between A/C control module and fuse.

9. CHECK A/C CONTROL MODULE GROUND CIRCUIT (OPEN CIRCUIT)  .

   Measure the resistance of harness between A/C control module connector and chassis ground.

   Connector and terminal 

   (i107) No. 5 - 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.