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Home >> Lexus >> 2021 >> UX 200 Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Headlights >> Lighting System (Exterior) (Diagnostic Codes (2 Of 2) & Circuit Tests) >> Lighting System >> Low Beam Headlight Circuit [10/2018 - 07/2022] >> Procedure

Low Beam Headlight Circuit [10/2018 - 07/2022]: Procedure

  1. PERFORM ACTIVE TEST USING TECHSTREAM 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Enter the following menus: Body Electrical / Main Body / Active Test.
    5. Perform the Active Test according to the display on the Techstream.

      Body Electrical > Main Body > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Headlight Relay Low beam headlights OFF or ON -

      Body Electrical > Main Body > Active Test 

      Tester Display
      Headlight Relay

      OK

      Low beam headlights illuminate.

      Result

      Result Proceed to
      OK A
      NG (for LH Side) B
      NG (for RH Side) C

    Result: 

    A 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2018 - 10/2019]  Refer to  PROBLEM SYMPTOMS TABLE [10/2019 - 10/2020]  Refer to  PROBLEM SYMPTOMS TABLE [10/2020 - 07/2022] 

    Result: 

    C 

    See step  9

    Result: 

    B 

    See step  2

  2. INSPECT HEADLIGHT ASSEMBLY LH (LO TERMINAL VOLTAGE) 
    GTY786514Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Headlight Assembly LH)
    1. Disconnect the headlight assembly LH connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A17-5 (LO) - Body ground Light control switch in head position 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  4

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY LH - BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A17-6 (E) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEADLIGHT ASSEMBLY LH. Refer to  DISASSEMBLY [10/2018 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  4. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - HEADLIGHT ASSEMBLY LH) 
    1. Remove the No. 1 integration relay.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      FOR HV MODEL

      Tester Connection Condition Specified Condition
      2B-1 - A17-5 (LO) Always Below 1 Ω
      2B-1 or A17-5 (LO) - Body ground Always 10 kΩ or higher
      FOR GASOLINE MODEL

      Tester Connection Condition Specified Condition
      1B-1 - A17-5 (LO) Always Below 1 Ω
      1B-1 or A17-5 (LO) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. INSPECT NO. 1 INTEGRATION RELAY 
    1. Remove the No. 1 integration relay from the No. 1 engine room relay block.

      Refer to REMOVAL [10/2018 - 07/2022]

    2. Inspect the No. 1 integration relay.

      Refer to INSPECTION [10/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE NO. 1 INTEGRATION RELAY. Refer to  REMOVAL [10/2018 - 07/2022] 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (POWER SOURCE - NO. 1 INTEGRATION RELAY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      FOR HV MODEL

      Tester Connection Switch Condition Specified Condition
      2A-5 - Body ground Ignition switch off 11 to 14 V
      FOR GASOLINE MODEL

      Tester Connection Condition Specified Condition
      1A-5 - Body ground Always 11 to 14 V
      GTY822885Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *A for HV Model
      *B for Gasoline Model
      *a Component without harness connected
      (to No. 1 Integration Relay)

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY) 
    1. Disconnect the 4C instrument panel junction block assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      FOR HV MODEL

      Tester Connection Condition Specified Condition
      2B-2 - 4C-31 Always Below 1 Ω
      2B-2 or 4C-31 - Body ground Always 10 kΩ or higher
      FOR GASOLINE MODEL

      Tester Connection Condition Specified Condition
      1B-2 - 4C-31 Always Below 1 Ω
      1B-2 or 4C-31 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY 
    1. Remove the instrument panel junction block assembly.

      Refer to REMOVAL [10/2018 - 07/2022]

    2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

      Refer to REMOVAL [10/2018 - 07/2022]

    3. Measure the resistance according to the value(s) in the table below.
      GTY809892Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Instrument Panel Junction Block Assembly)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      4C-31 - MB-15 (HRLY) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2018 - 07/2022] 

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022] 

  9. INSPECT HEADLIGHT ASSEMBLY RH (LO TERMINAL VOLTAGE) 
    1. Disconnect the headlight assembly RH connector.
      GTY786510Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Headlight Assembly RH)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A18-5 (LO) - Body ground Light control switch in head position 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  10

  10. CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY RH - BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A18-6 (E) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEADLIGHT ASSEMBLY RH. Refer to  DISASSEMBLY [10/2018 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  11. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - HEADLIGHT ASSEMBLY RH) 
    1. Remove the No. 1 integration relay.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      FOR HV MODEL

      Tester Connection Condition Specified Condition
      2A-12 - A18-5 (LO) Always Below 1 Ω
      2A-12 or A18-5 (LO) - Body ground Always 10 kΩ or higher
      FOR GASOLINE MODEL

      Tester Connection Condition Specified Condition
      1A-12 - A18-5 (LO) Always Below 1 Ω
      1A-12 or A18-5 (LO) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  12

  12. INSPECT NO. 1 INTEGRATION RELAY 
    1. Remove the No. 1 integration relay from the No. 1 engine room relay block.

      Refer to REMOVAL [10/2018 - 07/2022]

    2. Inspect the No. 1 integration relay.

      Refer to INSPECTION [10/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE NO. 1 INTEGRATION RELAY. Refer to  REMOVAL [10/2018 - 07/2022] 

    Result: 

    OK 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (POWER SOURCE - NO. 1 INTEGRATION RELAY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      FOR HV MODEL

      Tester Connection Switch Condition Specified Condition
      2B-8 - Body ground Ignition switch off 11 to 14 V
      FOR GASOLINE MODEL

      Tester Connection Condition Specified Condition
      1B-8 - Body ground Always 11 to 14 V
      GTY817416Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *A for HV Model
      *B for Gasoline Model
      *a Component without harness connected
      (to No. 1 Integration Relay)

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  14

  14. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)) 
    1. Disconnect the F40 main body ECU (multiplex network body ECU) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      FOR HV MODEL

      Tester Connection Condition Specified Condition
      2A-11 - F40-12 (HRY2) Always Below 1 Ω
      2A-11 or F40-12 (HRY2) - Body ground Always 10 kΩ or higher
      FOR GASOLINE MODEL

      Tester Connection Condition Specified Condition
      1A-11 - F40-12 (HRY2) Always Below 1 Ω
      1A-11 or F40-12 (HRY2) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2018 - 07/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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