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Home >> Toyota >> 2021 >> Mirai XLE >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System (W/O Headlight Ecu) - Diagnostic Codes & Circuit Tests >> LIGHTING SYSTEM (w/o Headlight ECU) >> High Beam Headlight Circuit [11/2020 - 12/2023] >> Procedure

High Beam Headlight Circuit [11/2020 - 12/2023]: Procedure

  1. 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
      Head Light Hi High beam headlights OFF or ON -

      Body Electrical > Main Body > Active Test 

      Tester Display
      Head Light Hi

      OK

      High 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 [11/2020 - 12/2023] 

    Result: 

    NG 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (DIMMER RELAY - HEADLIGHT ASSEMBLY LH) 
    1. Remove the DIMMER relay.
    2. Disconnect the A29 headlight assembly LH connector.
    3. Disconnect the A28 headlight assembly RH connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 (DIMMER relay) - A29-6 (SOL) Always Below 1 Ω
      3 (DIMMER relay) or A29-6 (SOL) - Body ground Always 10 kΩ or higher
      3 (DIMMER relay) or A28-6 (SOL) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. INSPECT DIMMER RELAY 

    Refer to ON-VEHICLE INSPECTION [11/2020 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE DIM RELAY 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (POWER SOURCE - DIMMER RELAY) 
    1. Remove the DIMMER relay.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      2 (DIMMER relay) - Body ground Ignition switch off 11 to 14 V
      5 (DIMMER 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  5

  5. CHECK HARNESS AND CONNECTOR (DIMMER RELAY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)) 
    1. Remove the DIMMER relay.
    2. Disconnect the D11 main body ECU (multiplex network body ECU) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (DIMMER relay) - D11-13 (DIM) Always Below 1 Ω
      1 (DIMMER relay) or D11-13 (DIM) - 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 [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR