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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Body & Frame >> Door Locks >> Smart Key System (For Start, Except HV) - Diagnostic Codes (2 Of 2) & Symptom Tests (1 Of 2) >> SMART KEY SYSTEM (for Start Function, Gasoline Model) >> DTC B279A-12: Engine Immobilizer System Circuit Short to Battery [12/2019 - 10/2021] >> Procedure

DTC B279A-12: Engine Immobilizer System Circuit Short to Battery [12/2019 - 10/2021]: Procedure

  1. CHECK CONNECTION OF CONNECTOR 
    1. Turn the ignition switch off.
    2. Check that the connectors are properly connected to the ECM and certification ECU (smart key ECU assembly).

      OK

      Connectors are properly connected.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    OK 

    See step  2

  2. CHECK WHETHER ENGINE STARTS 
    1. Check that the engine starts.

      OK

      Engine starts normally.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

    Result: 

    NG 

    See step  3

  3. CHECK ECM 
    1. Measure the voltage according to the value(s) in the table below.
      GTY865531Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Certification ECU (Smart Key ECU Assembly))

      Standard Voltage

      Tester Connection Condition Specified Condition
      A19-4 (EFIO) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  4

  4. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (TERMINAL EFIO) 
    1. Connect the A19 certification ECU (smart key ECU assembly) connector.
    2. Using an oscilloscope, check the waveform.
      GTY851425Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Certification ECU (Smart Key ECU Assembly))      		 *b Waveform
      *c Approximately 160 ms. *d Approximately 270 ms.

      Measurement Condition

      Tester Connection Condition Tool Setting Specified Condition
      A19-4 (EFIO) - Body ground Ignition switch turned to ON using registered electrical key transmitter sub-assembly 2 V/DIV., 500 ms./DIV. Pulse generation
      (See waveform)

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [12/2019 - 09/2020]  , or refer to  REMOVAL [09/2020 - 10/2022] 

    Result: 

    NG 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [12/2019 - 11/2023] 

  5. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ECM) 
    1. Disconnect the A28 ECM connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A19-4 (EFIO) - A28-59 (IMI) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [12/2019 - 09/2020]  , or refer to  REMOVAL [09/2020 - 10/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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