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Home >> Lexus >> 2021 >> LS 500 Base, RWD >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Exterior Lights >> Lighting System (Ext) - Diagnostic Codes (2 Of 3) >> Lighting System >> DTC B242F-14: ECUB Circuit Short to Ground or Open [10/2023 - ] >> Procedure

DTC B242F-14: ECUB Circuit Short to Ground or Open [10/2023 - ]: Procedure

  1. CLEAR DTC 
    1. Clear the DTCs.

      Body Electrical > Headlight Control > Clear DTCs 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  2

  2. CHECK FOR DTC 

    Pre-procedure1

    1. Turn ignition switch to ON.
    2. Wait 10 seconds or more.

      Procedure1

    3. Check for DTCs.

      Body Electrical > Headlight Control > Trouble Codes 

      Result

      Result Proceed to
      B242F-14 is output A
      B242F-14 is not output B

      Post-procedure1

    4. None

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  3

  3. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Normal Condition Diagnostic Note
      Headlight ECU/LDM LH Power Supply Fuse Shut Off Status Headlight ECU sub-assembly LH fuse condition OFF or ON OFF: Fuse not shut off
      ON: Fuse shut off

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM LH Power Supply Fuse Shut Off Status

      OK

      The Data List value displays "OFF".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  4

  4. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Normal Condition Diagnostic Note
      Headlight ECU/LDM LH Power Supply Signal Headlight ECU sub-assembly LH power supply signal OFF or ON OFF: Headlight ECU sub-assembly LH is not input
      ON: Headlight ECU sub-assembly LH is input

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM LH Power Supply Signal

      OK

      The Data List value displays "ON".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  8

    Result: 

    OK 

    See step  5

  5. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Normal Condition Diagnostic Note
      Headlight ECU/LDM LH Power Supply Output Headlight ECU sub-assembly LH power supply output OFF or ON OFF: Headlight ECU sub-assembly LH has no power supply
      ON: Headlight ECU sub-assembly LH has power supply

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM LH Power Supply Output

      OK

      The Data List value displays "ON".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    OK 

    See step  6

  6. INSPECT HEADLIGHT ECU SUB-ASSEMBLY LH (ECUB TERMINAL VOLTAGE) 

    Pre-procedure1

    1. Disconnect the A130 headlight ECU sub-assembly LH connector.

      Procedure1

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A130-13 (ECUB) - Body ground Ignition switch ON 9.5 to 14 V

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    OK 

    REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH. Refer to  REMOVAL [10/2020 - ] 

    Result: 

    NG 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU - HEADLIGHT ECU SUB-ASSEMBLY LH) 

    Pre-procedure1

    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the A61 No. 1 semiconductor power integration ECU connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      A61-1 (L) - A130-13 (ECUB) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  8. INSPECT NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU 

    Pre-procedure1

    1. Disconnect the 8E power distribution box assembly connector.

      Procedure1

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      8E-6 - Body ground Always 6 to 14V

      Result

      Proceed to
      OK
      NG
      GTY1233784Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Power Distribution Box Assembly)

      Post-procedure1

    3. None

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  9

  9. INSPECT POWER DISTRIBUTION BOX ASSEMBLY 

    Pre-procedure1

    1. Remove the main body ECU (multiplex network body ECU) from the power distribution box assembly.

      HINT: 

      Refer to REMOVAL [10/2023 - ]

      Procedure1

    2. Measure the resistance according to the value(s) in the table below.
      GTY1235524Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Power Distribution Box Assembly)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      8E-6 - MB-8 (HRLY) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPLACE POWER DISTRIBUTION BOX ASSEMBLY. Refer to  REMOVAL [10/2023 - ] 

  10. CHECK HARNESS AND CONNECTOR (NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU - POWER DISTRIBUTION BOX ASSEMBLY) 

    Pre-procedure1

    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the A61 No. 1 semiconductor power integration ECU connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      8E-6 - A61-15 (-S) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  11. READ VALUE USING GTS 

    Pre-procedure1

    1. Disconnect the A130 headlight ECU sub-assembly LH connector.
    2. Wait for 15 seconds after turning the ignition switch off.

      Procedure1

    3. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Normal Condition Diagnostic Note
      Headlight ECU/LDM LH Power Supply Fuse Shut Off Status Headlight ECU sub-assembly LH fuse condition OFF or ON OFF: Fuse not shut off
      ON: Fuse shut off

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM LH Power Supply Fuse Shut Off Status

      OK

      The Data List value displays "OFF".

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH. Refer to  REMOVAL [10/2020 - ] 

    Result: 

    NG 

    See step  12

  12. CHECK HARNESS AND CONNECTOR (NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU - HEADLIGHT ECU SUB-ASSEMBLY LH) 

    Pre-procedure1

    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the A61 semiconductor power integration ECU connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      A61-1 (L) or A130-13 (ECUB) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  13. CLEAR DTC 
    1. Clear the DTCs.

      Body Electrical > Headlight Control (Sub) > Clear DTCs 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  14

  14. CHECK FOR DTC 

    Pre-procedure1

    1. Turn ignition switch to ON.
    2. Wait 10 seconds or more.

      Procedure1

    3. Check for DTCs.

      Body Electrical > Headlight Control (Sub) > Trouble Codes 

      Result

      Result Proceed to
      B242F-14 is output A
      B242F-14 is not output B

      Post-procedure1

    4. None

    Result: 

    B 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2023 - ] 

    Result: 

    A 

    See step  15

  15. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Headlight ECU/LDM RH Power Supply Fuse Shut Off Status Headlight ECU sub-assembly RH fuse condition OFF or ON OFF: Fuse not shut off
      ON: Fuse shut off      		 -

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM RH Power Supply Fuse Shut Off Status

      OK

      The Data List value displays "OFF".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  23

    Result: 

    OK 

    See step  16

  16. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Headlight ECU/LDM RH Power Supply Signal Headlight ECU sub-assembly RH power supply signal OFF or ON OFF: Headlight ECU sub-assembly RH is not input
      ON: Headlight ECU sub-assembly RH is input      		 -

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM RH Power Supply Signal

      OK

      The Data List value displays "ON".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  20

    Result: 

    OK 

    See step  17

  17. READ VALUE USING GTS 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Headlight ECU/LDM RH Power Supply Output Headlight ECU sub-assembly RH power supply output OFF or ON OFF: Headlight ECU sub-assembly RH has no power supply
      ON: Headlight ECU sub-assembly RH has power supply      		 -

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM RH Power Supply Output

      OK

      The Data List value displays "ON".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    OK 

    See step  18

  18. INSPECT HEADLIGHT ECU SUB-ASSEMBLY RH (ECUB TERMINAL VOLTAGE) 

    Pre-procedure1

    1. Disconnect the A131 headlight ECU sub-assembly LH connector.

      Procedure1

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A131-13 (ECUB) - Body ground Ignition switch ON 9.5 to 14 V

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    OK 

    REPLACE HEADLIGHT ECU SUB-ASSEMBLY RH. Refer to  REMOVAL [10/2020 - ] 

    Result: 

    NG 

    See step  19

  19. CHECK HARNESS AND CONNECTOR (NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU - HEADLIGHT ECU SUB-ASSEMBLY LH) 

    Pre-procedure1

    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the A61 No. 1 semiconductor power integration ECU connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      A61-2 (HI) - A131-13 (ECUB) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  20. INSPECT NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU 

    Pre-procedure1

    1. Disconnect the 8E power distribution box assembly connector.

      Procedure1

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      8E-10 - Body ground Always 6 to 14V

      Result

      Proceed to
      OK
      NG
      GTY1233784Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Power Distribution Box Assembly)

      Post-procedure1

    3. None

    Result: 

    NG 

    See step  22

    Result: 

    OK 

    See step  21

  21. INSPECT POWER DISTRIBUTION BOX ASSEMBLY 

    Pre-procedure1

    1. Remove the main body ECU (multiplex network body ECU) from the power distribution box assembly.

      HINT: 

      Refer to REMOVAL [10/2023 - ]

      Procedure1

    2. Measure the resistance according to the value(s) in the table below.
      GTY1235525Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Power Distribution Box Assembly)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      8E-10 - MB-9 (HRY2) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPLACE POWER DISTRIBUTION BOX ASSEMBLY. Refer to  REMOVAL [10/2023 - ] 

  22. CHECK HARNESS AND CONNECTOR (NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU - POWER DISTRIBUTION BOX ASSEMBLY) 

    Pre-procedure1

    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the A61 semiconductor power integration ECU connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      8E-10 - A61-14 (-S) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  23. READ VALUE USING GTS 

    Pre-procedure1

    1. Disconnect the A131 headlight ECU sub-assembly RH connector.
    2. Wait for 15 seconds after turning the ignition switch off.

      Procedure1

    3. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Normal Condition Diagnostic Note
      Headlight ECU/LDM RH Power Supply Fuse Shut Off Status Headlight ECU sub-assembly RH fuse condition OFF or ON OFF: Fuse not shut off
      ON: Fuse shut off

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      Headlight ECU/LDM RH Power Supply Fuse Shut Off Status

      OK

      The Data List value displays "OFF".

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE HEADLIGHT ECU SUB-ASSEMBLY RH. Refer to  REMOVAL [10/2020 - ] 

    Result: 

    NG 

    See step  24

  24. CHECK HARNESS AND CONNECTOR (NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU - HEADLIGHT ECU SUB-ASSEMBLY LH) 

    Pre-procedure1

    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the A61 semiconductor power integration ECU connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      A61-2 (L) or A131-13 (ECUB) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    REPLACE NO. 1 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [10/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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