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Home >> Toyota >> 2021 >> Mirai XLE >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System (W/ Headlight Ecu) - Diagnostic Codes (1 Of 2) >> LIGHTING SYSTEM (w/ Headlight ECU) >> DTC B242F: Open in B Power Line [11/2021 - 12/2023] >> Procedure

DTC B242F: Open in B Power Line [11/2021 - 12/2023]: Procedure

  1. CLEAR DTC 

    Pre-procedure1

    • Turn the ignition switch to ON.
    • Clear the DTCs.

      for Mono Camera Type:

      Body Electrical > HL AutoLeveling > Clear DTCs 

      Body Electrical > HL AutoLeveling (Sub) > Clear DTCs 

      for Stereo Camera Type:

      Body Electrical > AFS > Trouble Codes 

      Body Electrical > AFS (Sub) > Trouble Codes 

      Result

      Proceed to
      NEXT

    Post-procedure1

    • None

    Result: 

    NEXT 

    See step  2

  2. CHECK FOR DTC 

    Pre-procedure1

    • Turn the ignition switch to ON.
    • Wait 10 seconds or more.
    • Check for DTCs.

      Mono Camera Type:

      Body Electrical > HL AutoLeveling > Trouble Codes 

      Body Electrical > HL AutoLeveling (Sub) > Trouble Codes 

      for Stereo Camera Type:

      Body Electrical > AFS > Trouble Codes 

      Body Electrical > AFS (Sub) > Trouble Codes 

      Result

      Result Proceed to
      B242F is not output A
      Only B242F for headlight ECU sub-assembly LH is output B
      Only B242F for headlight ECU sub-assembly RH is output C

    Post-procedure1

    • None

    Result: 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2020 - ] 

    Result: 

    See step  10

    Result: 

    See step  3

  3. CHECK HEADLIGHT ECU SUB-ASSEMBLY LH (ECUB TERMINAL VOLTAGE) 

    Pre-procedure1

    • Disconnect the A96 headlight ECU sub-assembly LH connector.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A96-13 (ECUB) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY LH - BODY GROUND) 

    Pre-procedure1

    • Disconnect the A96 headlight ECU sub-assembly LH connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A96-12 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH. Refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  5. INSPECT H-LP LH RELAY 

    Pre-procedure1

    • Remove the H-LP LH relay.

    Post-procedure1

    • None

    Result: 

    NG 

    REPLACE H-LP LH RELAY 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - HEADLIGHT ECU SUB-ASSEMBLY LH) 

    Pre-procedure1

    • Remove the H-LP LH relay.
    • Disconnect the A96 headlight ECU sub-assembly LH connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      5 (H-LP LH relay) - A96-13 (ECUB) Always Below 1 Ω
      5 (H-LP LH relay) or A96-13 (ECUB) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - POWER SOURCE) 

    Pre-procedure1

    • Remove the H-LP LH relay.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      1 (H-LP LH relay) - Body ground Ignition switch off 11 to 14 V
      3 (H-LP LH relay) - Body ground Ignition switch off 11 to 14 V
      GTY510431Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to H-LP LH Relay)

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - DRIVER SIDE JUNCTION BLOCK ASSEMBLY) 

    Pre-procedure1

    • Remove the H-LP LH relay.
    • Disconnect the 4F driver side junction block assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2 (H-LP LH relay) - 4F-19 Always Below 1 Ω
      2 (H-LP LH relay) or 4F-19 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. INSPECT DRIVER SIDE JUNCTION BLOCK ASSEMBLY 

    Pre-procedure1

    • Remove the driver side junction block assembly.

      HINT: 

      Refer to REMOVAL [11/2021 - 12/2022] , or refer to REMOVAL [12/2022 - 12/2023]

      GTY932726Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Driver Side Junction Block Assembly)
      - -
    • Remove the main body ECU (multiplex network body ECU) from the driver side junction block assembly.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      4F-19 - A-15 (HRLY) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023] 

    Result: 

    NG 

    REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023] 

  10. CHECK HEADLIGHT ECU SUB-ASSEMBLY RH (ECUB TERMINAL VOLTAGE) 

    Pre-procedure1

    • Disconnect the A97 headlight ECU sub-assembly RH connector.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A97-13 (ECUB) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY RH - BODY GROUND) 

    Pre-procedure1

    • Disconnect the A97 headlight ECU sub-assembly RH connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A97-12 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE HEADLIGHT ECU SUB-ASSEMBLY RH. Refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  12. INSPECT H-LP RH RELAY 

    Pre-procedure1

    • Remove the H-LP RH relay.

    Post-procedure1

    • None

    Result: 

    NG 

    REPLACE H-LP RH RELAY 

    Result: 

    OK 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - HEADLIGHT ECU SUB-ASSEMBLY RH) 

    Pre-procedure1

    • Remove the H-LP RH relay.
    • Disconnect the A97 headlight ECU sub-assembly RH connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 (H-LP RH relay) - A97-13 (ECUB) Always Below 1 Ω
      3 (H-LP RH relay) or A97-13 (ECUB) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  14

  14. CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - POWER SOURCE) 

    Pre-procedure1

    • Remove the H-LP RH relay.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      1 (H-LP RH relay) - Body ground Ignition switch off 11 to 14 V
      5 (H-LP RH relay) - Body ground Ignition switch off 11 to 14 V
      GTY510431Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to H-LP RH Relay)

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  15

  15. CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)) 

    Pre-procedure1

    • Remove the H-LP RH relay.
    • Disconnect the D11 main body ECU (multiplex network body ECU) connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2 (H-LP RH relay) - D11-12 (HRY2) Always Below 1 Ω
      2 (H-LP RH relay) or D11-12 (HRY2) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR