Communication For Initializing Impossible

Diagnosis: 

Open or short circuit in data link connector

Trouble symptom: 

Subaru Select Monitor communication failure

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK POWER SUPPLY CIRCUIT  .

   Connect DST-i or a general scan tool to the data link connector.

   Is the DST-i or the general scan tool turned to ON?

   Yes: Go to  4.

   No: GO to  2.

2. CHECK POWER SUPPLY CIRCUIT  .

   Measure the voltage between data link connector and chassis ground.

   Connector & terminal

   (B40) 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. 13)
3. CHECK HARNESS BETWEEN DATA LINK CONNECTOR AND CHASSIS GROUND  .
   1. Turn the ignition switch to OFF.
   2. Measure the resistance of harness between data link connector and chassis ground.

      Connector & terminal

      (B40) No. 4 - Chassis ground:

      (B40) No. 5 - Chassis ground:

   Is the resistance less than 5 Ω?

   Yes: Repair the poor contact of data link connector.

   NO: Repair the harness and connector.

   NOTE: In this case, repair the following item:

   • Open circuit in harness between ECM connector and data link connector
   • Open circuit of harness between ECM connector and engine ground
   • Poor contact of ECM connector
   • Poor contact of joint connector
4. CHECK HARNESS BETWEEN ECM AND DATA LINK CONNECTOR  .
   1. Disconnect the connectors from ECM, DCCD CONTROL MODULE, VDC CONTROL MODULE, airbag CONTROL MODULE, impact sensor, TPMS & keyless entry CONTROL MODULE, and body integrated unit.
      CAUTION: When disconnecting the connector from airbag CONTROL MODULE, always follow the precautions on AB article. Ref. to AIRBAG SYSTEM>General Description>CAUTION .
   2. Measure the resistance of harness between ECM connector and data link connector.

      Connector & terminal

      (B135) No. 14 - (B40) No. 7:

   Is the resistance less than 1 Ω?

   Yes: Go to  5.

   No: Repair the open circuit of harness between ECM connector and data link connector.

5. CHECK HARNESS BETWEEN ECM AND DATA LINK CONNECTOR  .

   Measure the resistance between data link connector and chassis ground.

   Connector & terminal

   (B40) No. 7 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes: Repair the poor contact of ECM connector or data link connector.

   No: Repair the short circuit to ground in harness between ECM connector and data link connector.