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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 [11/2023 - ] >> Procedure

DTC B279A-12: Engine Immobilizer System Circuit Short to Battery [11/2023 - ]: Procedure

  1. CHECK CONNECTION OF CONNECTOR 

    Pre-procedure1

    1. Turn the ignition switch off.

      Procedure1

    2. Check that the connectors are properly connected to the ECM and ID code box (immobilizer code ECU).

      OK

      Connectors are properly connected.

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    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 (TERMINAL EFIO) 
    1. Measure the voltage according to the value(s) in the table below.
      GTY1181229Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (ID Code Box (Immobilizer Code ECU))

      Standard Voltage

      Tester Connection Condition Specified Condition
      H53-4 (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 ID CODE BOX (IMMOBILIZER CODE ECU) (TERMINAL EFIO) 
    1. Using an oscilloscope, check the waveform.
      GTY1178428Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      ID Code Box (Immobilizer Code ECU)      		 *b Waveform 1
      *c Approximately 160 ms. *d Approximately 270 ms.

      OK

      Tester Connection Condition Tool Setting Specified Condition
      H53-4 (EFIO) - Body ground Within 3 seconds of engine start or within 3 seconds of ignition switch turned to ON after cable disconnected and reconnected to auxiliary battery 2 V/DIV., 500 ms./DIV. Pulse generation
      (See waveform 1)

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [11/2023 - ] 

    Result: 

    NG 

    REPLACE ID CODE BOX (IMMOBILIZER CODE ECU). Refer to  REMOVAL [11/2023 - ] 

  5. CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILIZER CODE ECU) - ECM) 

    Pre-procedure1

    1. Disconnect the A83 ECM connector.
    2. Disconnect the H53 ID code box (immobilizer code ECU) connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      H53-4 (EFIO) - A83-38 (IMI) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [11/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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