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Home >> Toyota >> 2019 >> Yaris LE >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System - Diagnostic Codes (12 Of 13) >> SFI System >> DTC U0074-00: Control Module Communication Bus "B" Off [07/2015 - 08/2018] >> Procedure
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DTC U0074-00: Control Module Communication Bus "B" Off [07/2015 - 08/2018]: Procedure

  1. VERIFY RELATED PENDING CODE AND/OR DTC 
    1. Switch the ignition off, then ON (engine off).
    2. Perform the Pending Trouble Code Access Procedure and DTC Reading Procedure.

      Refer to ON-BOARD DIAGNOSTIC TEST [07/2015 - ]

      Powertrain > Engine > Trouble Codes 

    3. Are any other PENDING CODEs and/or DTCs present?

      Result

      Result
      Yes
      No

    Result: 

    Yes 

    GO TO THE APPLICABLE PENDING CODE OR DTC INSPECTION. 

    1. Refer to DIAGNOSTIC TROUBLE CODE CHART [07/2015 - 08/2018]

    Result: 

    No 

    See step  2

  2. CONFIRM TCM DTC 
    1. Perform the TCM DTC inspection using the Techstream.

      Refer to ON-BOARD DIAGNOSTIC SYSTEM DTC INSPECTION [07/2015 - ]

      Powertrain > Transmission > Trouble Codes 

    2. Are any DTCs present?

      Result

      Result Proceed to
      DTC U007400 or U011500 is displayed: Yes (A)
      DTC other than U007400 and U011500 is displayed: Yes (B)
      - No

    Result: 

    Yes (A) 

    See step  6

    Result: 

    Yes (B) 

    GO TO THE APPLICABLE DTC INSPECTION. 

    1. Refer to DIAGNOSTIC TROUBLE CODE CHART [07/2015 - 08/2019]

    Result: 

    No 

    See step  7

  3. VERIFY DTC TROUBLESHOOTING COMPLETED 
    1. Clear the DTC from the ECM memory using the Techstream.

      Refer to CLEARING DTC [07/2015 - ]

      Powertrain > Engine > Clear DTCs 

    2. Implement the repeatability verification procedure.
    3. Perform the DTC Reading Procedure.

      Refer to ON-BOARD DIAGNOSTIC TEST [07/2015 - ]

      Powertrain > Engine > Trouble Codes 

    4. Is the same DTC present?

      Result

      Result
      Yes
      No

    Result: 

    Yes 

    See step  5

    Result: 

    No 

    See step  4

  4. VERIFY AFTER REPAIR PROCEDURE 
    1. Perform the "AFTER REPAIR PROCEDURE".

      Refer to AFTER REPAIR PROCEDURE [07/2015 - ]

    2. Are any DTCs present?

      Result

      Result
      Yes
      No

    Result: 

    No 

    DTC TROUBLESHOOTING COMPLETED. 

    Result: 

    Yes 

    GO TO THE APPLICABLE DTC INSPECTION. 

    1. Refer to DIAGNOSTIC TROUBLE CODE CHART [07/2015 - 08/2018]
  5. REPLACE THE ECM. 
    1. Refer to REMOVAL [07/2015 - ]
    2. Then go to the next step.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  4

  6. CAN COMMUNICATION LINE CAN BE CONSIDERED THE CAUSE. 
    1. Repair or replace the wiring harness between ECM and TCM, then go to the next step.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  3

  7. TCM CAN BE CONSIDERED THE CAUSE. 
    1. Replace the control valve body, then go to the next step.

      Refer to REMOVAL [07/2015 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  3

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