ENGINE IMMOBILISER SYSTEM (w/ Smart Entry and Start System), Diagnostic DTC:B279A

DTC Code DTC Name
B279A Theft Deterrent System Communication Line High Fixation

DESCRIPTION

If the communication line (EFIO - IMI) to the certification ECU (smart key ECU assembly) is stuck high output (e.g. shorted to +B), the ECM stores this DTC.

DTC No. DTC Detection Condition Trouble Area
B279A When the communication line (EFIO - IMI) between ECM and certification ECU (smart key ECU assembly) is stuck high output.

  • Wire harness or connector

  • Certification ECU (Smart key ECU assembly)

  • ECM

WIRING DIAGRAM

A01EMPAE77

INSPECTION PROCEDURE

Note

If the certification ECU (smart key ECU assembly) is replaced, register the key (Refer to Service Bulletin).

PROCEDURE


  1. CHECK DTC OUTPUT


    1. Clear the DTCs Click here.

    2. Recheck for DTCs Click here.

      Tech Tips

      If any DTCs other than DTC B279A are output, troubleshoot those DTCs first.

      Result
      Result Proceed to
      DTC B279A is output A
      DTC B279A and other DTCs are output B

    B

    GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

    A

  2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ECM)


    1. Disconnect the certification ECU (smart key ECU assembly) connector.

    2. A01ELPDE06
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Certification ECU (Smart Key ECU Assembly))
      *2

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

    3. Measure the resistance and voltage according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      D25-35 (EFIO) - A49-11 (IMI) Always Below 1 Ω
      D25-35 (EFIO) - Body ground Always 10 kΩ or higher
      Standard Voltage
      Tester Connection Condition Specified Condition
      D25-35 (EFIO) - Body ground Always Below 1 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)


    1. Reconnect the certification ECU (smart key ECU assembly) connector.

    2. Reconnect the ECM connector.

    3. Using an oscilloscope, check the waveform.

      A01EJ89E01
      Waveform (Reference)
      Item Content
      Terminal No. (Symbol) D25-35 (EFIO) - D25-15 (E)
      Tool Setting 5 V/DIV., 100 msec./DIV.
      Condition Engine switch on (IG)
      OK
      Waveform is output normally (see illustration).
      Text in Illustration
      *1

      Component with harness connected

      (Certification ECU (Smart Key ECU Assembly))
      *2 GND

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Click here

    OK

    REPLACE ECM Click here

  4. REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)


    1. Replace the certification ECU (smart key ECU assembly.

      Tech Tips

      Refer to Service Bulletin.


    NEXT

  5. KEY REGISTRATION


    1. Register the key.

      Tech Tips

      Refer to Service Bulletin.


    NEXT

  6. REGISTER ECU COMMUNICATION ID


    1. Register the ECU communication ID.

      Tech Tips

      Refer to Service Bulletin.


    NEXT

  7. CHECK DTC OUTPUT


    1. Clear the DTCs Click here.

    2. Recheck for DTCs Click here.

      OK
      DTC B279A is not output.

    NG

    REPLACE ECM Click here

    OK

    END (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) WAS DEFECTIVE)