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Home >> Toyota >> 2019 >> Sequoia SR5, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Headlights >> Lighting System (Exterior) - Diagnostic Codes & Circuit Tests >> Lighting System >> Headlight Signal Circuit [08/2015 - 08/2017] >> Procedure

Headlight Signal Circuit [08/2015 - 08/2017]: Procedure

  1. PERFORM ACTIVE TEST USING TECHSTREAM (HEADLIGHT) 
    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 / Headlight Relay
    5. Check that the headlight (low) turn on/off.
      MAIN BODY ECU

      Tester Display Test Part Control Range Diagnostic Note
      Headlight Relay Headlight ON or OFF -

      OK

      Headlight low beams turn on/off.

    Result: 

    OK 

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE 

    (Refer to PROBLEM SYMPTOMS TABLE [08/2015 - 08/2017] )

    Result: 

    NG 

    See step  2

  2. INSPECT FUSE (HEAD LL, HEAD RL) 
    1. Remove the HEAD LL and HEAD RL fuses from the engine room relay block.
      GTY551059Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      HEAD LL fuse Always Below 1 Ω
      HEAD RL fuse Always Below 1 Ω
    3. Reinstall the HEAD LL and HEAD RL fuses.

    Result: 

    NG 

    REPLACE FUSE 

    Result: 

    OK 

    See step  3

  3. INSPECT HEADLIGHT (LOW) BULB 
    1. Temporarily replace the headlight (low) bulb with a new or normally functioning one (Refer to PROCEDURE - Step 5 ).
    2. Check that the headlight (low) turn on.

      OK

      Headlight (low) turn on.

    Result: 

    OK 

    END 

    Result: 

    NG 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (HEADLIGHT LOW BULB - HEAD RELAY) 
    GTY604924Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. for LH:
      1. Disconnect the A12 headlight (low) LH connector.
      2. Measure the voltage according to the value(s) in the table below.

        Standard Voltage

        Tester Connection Switch Condition Specified Condition
        A12-2 - Body ground Light control switch HEAD, dimmer switch Low 11 to 14 V
        Light control switch HEAD, dimmer switch except Low Below 1 V
      3. Reinstall the headlight (low) LH connector.
    2. for RH:
      1. Disconnect the A13 headlight (low) RH connector.
      2. Measure the voltage according to the value(s) in the table below.

        Standard Voltage

        Tester Connection Switch Condition Specified Condition
        A13-2 - Body ground Light control switch HEAD, dimmer switch Low 11 to 14 V
        Light control switch HEAD, dimmer switch except Low Below 1 V
      3. Reinstall the headlight (low) RH connector.

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (HEADLIGHT LOW BULB - BODY GROUND) 

    Result: 

    NG 

    See step  5

  5. INSPECT HEADLIGHT RELAY (HEAD) 
    GTY549231Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the HEAD relay from the engine room relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 - 5 When battery voltage is not applied to terminals 1 and 2 10 kΩ or higher
      When battery voltage is applied to terminals 1 and 2 Below 1 Ω
    3. Reinstall the HEAD relay.

    Result: 

    NG 

    REPLACE HEAD RELAY 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (HEAD RELAY - BATTERY) 
    GTY220317Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the HEAD relay from the engine room relay block.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      HEAD relay terminal 1 - Body ground Always 11 to 14 V
      HEAD relay terminal 3 - Body ground Always 11 to 14 V
    3. Reinstall the HEAD relay.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (HEAD RELAY - HEADLIGHT LOW BULB) 
    1. Remove the HEAD relay from the engine room relay block.
      GTY552492Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. for LH:
      1. Disconnect the A12 headlight (low) LH connector.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        HEAD relay terminal 5 - A12-2 Always Below 1 Ω
        HEAD relay terminal 5 - Body ground Always 10 kΩ or higher
      3. Reinstall the headlight (low) LH connector.
    3. for RH:
      1. Disconnect the A13 headlight (low) RH connector.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        HEAD relay terminal 5 - A13-2 Always Below 1 Ω
        HEAD relay terminal 5 - Body ground Always 10 kΩ or higher
      3. Reinstall the headlight (low) RH connector.
    4. Reinstall the HEAD relay.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HEADLIGHT (HEADLIGHT RELAY - MAIN BODY ECU) 
    GTY599406Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the DB main body ECU connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      DB-18 - Body ground Always 11 to 14 V
    3. Reconnect the main body ECU connector.

    Result: 

    OK 

    REPLACE MAIN BODY ECU 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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