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Home >> Toyota >> 2021 >> Mirai XLE >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can Communication System - Diagnostic Codes (3 Of 3) & Circuit Tests (1 Of 8) >> Can Communication System >> Main Body ECU Communication Stop Mode [12/2022 - 12/2023] >> Procedure

Main Body ECU Communication Stop Mode [12/2022 - 12/2023]: Procedure

  1. CHECK FOR OPEN IN CAN BUS WIRE (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) BRANCH WIRE) 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
    2. Disconnect the D11 main body ECU (multiplex network body ECU) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D11-5 (CANH) - D11-4 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω

      Result

      Proceed to 
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A-11 (GND1) - Body ground Cable disconnected from negative (-) auxiliary battery terminal Below 1 Ω
      GTY1018541Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Driver Side Junction Block Assembly)
    2. Reconnect the cable to the negative (-) auxiliary battery terminal.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A-31 (BECU) - Body ground Ignition switch off 11 to 14 V
      A-30 (ACC) - Body ground Ignition switch ACC 11 to 14 V
      A-32 (IG) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)). Refer to  REMOVAL [12/2022 - 12/2023] 

    Result: 

    NG 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    1. Disconnect the 4L, 4K and 4D driver side junction assembly connectors.
      GTY972429Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Driver Side Junction Block Assembly)
      - -
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      4D-6 - Body ground Always Below 1 Ω
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      4L-1 - Body ground Ignition switch off 11 to 14 V
      4K-1 - Body ground Ignition switch off 11 to 14 V

      Result

      Proceed to 
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      4D-17 - Body ground Ignition switch ACC 11 to 14 V
      4D-18 - Body ground Ignition switch ON 11 to 14 V
      GTY972509Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Driver Side Junction Block Assembly)

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [12/2022 - 12/2023] 

    Result: 

    NG 

    GO TO SMART ENTRY AND START SYSTEM (for Start Function). Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2022 - 12/2023]