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DTC B1279: Lost Communication with Humidity/Rain Sensor LIN [12/2019 - 11/2023]: Procedure

  1. CHECK FOR DTC 
    1. Read the DTCs.

      Body Electrical > Main Body > Trouble Codes 

      Result

      Result Proceed to
      Only DTC B1279 is output A
      DTC B1279 and B1373 are output B

    Result: 

    B 

    GO TO DTC B1373. Refer to  DTC B1373: Lost Communication with Wiper System LIN BUS [12/2019 - 11/2023]  

    Result: 

    A 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) - RAIN SENSOR) 
    1. Disconnect the H42 main body ECU (multiplex network body ECU) connector.
    2. Disconnect the R4 rain sensor connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H42-3 (LIN3) - R4-3 (MPX) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) 
    GTY920045Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component without harness connected
    (Main Body ECU (Multiplex Network Body ECU)
    1. Check for voltage and pulses according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      H42-3 (LIN3) - Body ground Ignition switch ON Pulse generation

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (POWER SOURCE - RAIN SENSOR) 
    GTY869238Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Rain Sensor)
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      R4-4 (SIG) - Body ground Ignition switch off Below 1 V
      Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (RAIN SENSOR - BODY GROUND) 
    GTY869237Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Rain Sensor)
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      R4-2 (ES) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE RAIN SENSOR. Refer to  REMOVAL [12/2019 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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