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CAN Communication Circuit Check: Procedure: Notes

  1. DIAG-CAN 

    Trouble causes:

    • DIAG-CAN communication circuit is shorted to ground.
    • DIAG-CAN communication circuit is shorted to power supply.
    • DIAG-CAN communication circuit is shorted between lines.
    • Body integrated unit malfunction

    Wiring diagram: 

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

G13228856Courtesy of SUBARU OF AMERICA, INC.
CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to LAN SYSTEM (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .
NOTE: When measuring the resistance of CAN communication circuit, measure it in sleep status. To enter sleep status
  • With ignition switch OFF and key or switch operation stopped, keep the doors, trunk, and rear gate all closed for one minute or more.
  • On model with the keyless access with push button start, keep the access key 2 m or more away from the vehicle.
  1. CHECK BASIC DIAGNOSTIC PROCEDURE  .

    Check that the basic diagnosis has been performed up to STEP 3.

    NOTE: Possible defective parts can be narrowed easily by inspection using Subaru Select Monitor before performing "CHECK CAN COMMUNICATION CIRCUIT" using a tester.

    Was the basic diagnostic procedure performed?

    Yes  : Go to  2 .

    No  : Perform the basic diagnostic procedure. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

  2. CHECK FOR SHORT TO GROUND IN HARNESS BETWEEN DATA LINK CONNECTOR AND BODY INTEGRATED UNIT  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the body integrated unit connector.
    3. Using the tester, measure the resistance between data link connector and chassis ground.

      Connector & terminal 

      (i288) No. 6 - Chassis ground:

      (i288) No. 14 - Chassis ground:

    Is the resistance less than 10 Ω?

    Yes  : Repair or replace the short circuit to ground of the harness between data link connector and body integrated unit.

    No  : Go to  3 .

  3. CHECK FOR SHORT TO POWER SUPPLY IN HARNESS BETWEEN DATA LINK CONNECTOR AND BODY INTEGRATED UNIT  .
    1. Turn the ignition switch to ON.
    2. Using the tester, measure the voltage between data link connector and chassis ground.

      Connector & terminal 

      (i288) No. 6 (+) - Chassis ground (-):

      (i288) No. 14 (+) - Chassis ground (-):

    Is the voltage 5 V or less?

    Yes  : Go to  4 .

    No  : Repair or replace the short circuit to power supply of the harness between data link connector and body integrated unit.

  4. CHECK FOR SHORT BETWEEN LINES IN HARNESS BETWEEN DATA LINK CONNECTOR AND BODY INTEGRATED UNIT  .
    1. Turn the ignition switch to OFF.
    2. Using the tester, measure the resistance between terminals.

      Connector & terminal 

      (i288) No. 6 - (i288) No. 14:

    Is the resistance 1 MΩ or more?

    Yes  : Go to  5 .

    No  : Repair or replace the short circuit between lines of the harness between data link connector and body integrated unit.

  5. CHECK END RESISTANCE  .
    1. Connect the body integrated unit connector.
    2. Using a tester, measure the resistance between terminals of data link connector.

      Connector & terminal 

      (i288) No. 6 - (i288) No. 14:

    Is the resistance 114 - 126 Ω?

    Yes  : CAN communication circuit is normal.

    No  : Replace the body integrated unit. Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .

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