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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System (W/O AFS) - Symptom Tests & Circuit Tests (2 Of 2) >> LIGHTING SYSTEM (w/o AFS) >> LO-beam Headlight does not Illuminate [11/2023 - ] >> Procedure

LO-beam Headlight does not Illuminate [11/2023 - ]: Procedure

  1. CHECK LIGHTS 
    1. Check the illumination of each low beam light.

      Result

      Result Proceed to
      LH side low beam light does not illuminate A
      RH side low beam light does not illuminate B

    Result: 

    B 

    See step  10

    Result: 

    A 

    See step  2

  2. PERFORM ACTIVE TEST USING GTS 
    1. Perform the Active Test according to the display on the GTS.

      Body Electrical > Main Body > Active Test 

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

      Body Electrical > Main Body > Active Test 

      Tester Display
      Headlight Relay / Light Power Supply Relay

      OK

      Low beam headlights illuminate.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [11/2023 - ] 

    Result: 

    NG 

    See step  3

  3. INSPECT HEADLIGHT ASSEMBLY LH (LO TERMINAL VOLTAGE) 
    GTY846820Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Headlight Assembly LH)
    1. Disconnect the A66 headlight assembly LH connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A66-1 (LO) - Body ground Light control switch in head position 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  4

  4. 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
      A66-4 (E) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEADLIGHT ASSEMBLY LH. Refer to  REMOVAL [11/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  5. CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - HEADLIGHT ASSEMBLY LH) 
    1. Remove the H-LP LH relay.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 (H-LP LH relay) - A66-1 (LO) Always Below 1 Ω
      3 (H-LP LH relay) or A66-1 (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  6

  6. INSPECT H-LP LH RELAY 

    Refer to ON-VEHICLE INSPECTION [12/2019 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE H-LP LH RELAY 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (POWER SOURCE - H-LP LH RELAY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      2 (H-LP LH relay) - Body ground Ignition switch off 11 to 14 V
      5 (H-LP LH relay) - 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  8

  8. CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - POWER DISTRIBUTION BOX ASSEMBLY) 
    1. Disconnect the 8E power distribution box assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (H-LP LH relay) - 8E-6 Always Below 1 Ω
      1 (H-LP LH relay) or 8E-6 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK POWER DISTRIBUTION BOX ASSEMBLY 
    1. Remove the power distribution box assembly.

      Refer to REMOVAL [11/2023 - ]

      GTY1180255Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Power Distribution Box Assembly)      		 - -
    2. Remove the main body ECU (multiplex network body ECU) from the power distribution box assembly.

      Refer to REMOVAL [11/2023 - ]

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

      Standard Resistance

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

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2023 - ] 

    Result: 

    NG 

    REPLACE POWER DISTRIBUTION BOX ASSEMBLY. Refer to  REMOVAL [11/2023 - ] 

  10. PERFORM ACTIVE TEST USING GTS 
    1. Perform the Active Test according to the display on the GTS.

      Body Electrical > Main Body > Active Test 

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

      Body Electrical > Main Body > Active Test 

      Tester Display
      Headlight Relay / Light Power Supply Relay

      OK

      Low beam headlights illuminate.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [11/2023 - ] 

    Result: 

    NG 

    See step  11

  11. INSPECT HEADLIGHT ASSEMBLY RH (LO TERMINAL VOLTAGE) 
    GTY928088Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Headlight Assembly RH)
    1. Disconnect the A65 headlight assembly RH connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A65-1 (LO) - Body ground Light control switch in head position 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  13

    Result: 

    OK 

    See step  12

  12. 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
      A65-4 (E) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEADLIGHT ASSEMBLY RH. Refer to  REMOVAL [11/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  13. CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - HEADLIGHT ASSEMBLY RH) 
    1. Remove the H-LP RH relay.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 (H-LP RH relay) - A65-1 (LO) Always Below 1 Ω
      3 (H-LP RH relay) or A65-1 (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  14

  14. INSPECT H-LP RH RELAY 

    Refer to ON-VEHICLE INSPECTION [12/2019 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE H-LP RH RELAY 

    Result: 

    OK 

    See step  15

  15. CHECK HARNESS AND CONNECTOR (POWER SOURCE - H-LP RH RELAY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      2 (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

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  16

  16. CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - POWER DISTRIBUTION BOX ASSEMBLY) 
    1. Disconnect the 8E power distribution box assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (H-LP RH relay) - 8E-10 Always Below 1 Ω
      1 (H-LP RH relay) or 8E-10 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  17

  17. CHECK POWER DISTRIBUTION BOX ASSEMBLY 
    1. Remove the power distribution box assembly.

      Refer to REMOVAL [11/2023 - ]

      GTY1180256Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Power Distribution Box Assembly)      		 - -
    2. Remove the main body ECU (multiplex network body ECU) from the power distribution box assembly.

      Refer to REMOVAL [11/2023 - ]

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

      Standard Resistance

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

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2023 - ] 

    Result: 

    NG 

    REPLACE POWER DISTRIBUTION BOX ASSEMBLY. Refer to  REMOVAL [11/2023 - ] 

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