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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 >> Front Fog Light Circuit [08/2015 - 08/2017] >> Procedure

Front Fog Light Circuit [08/2015 - 08/2017]: Procedure

  1. PERFORM ACTIVE TEST USING TECHSTREAM (FRONT FOG LIGHT) 
    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 / Front Fog Light.
    5. Check that the front fog lights turn on/off.
      MAIN BODY

      Tester Display Test Part Control Range Diagnostic Note
      Front Fog Light Relay Front fog light ON or OFF -

      OK

      Front fog lights 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 (FOG) 
    1. Remove the FOG fuse from the engine room relay block.
      GTY551058Courtesy 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
      FOG fuse Always Below 1 Ω
    3. Reinstall the FOG fuse.

    Result: 

    NG 

    REPLACE FUSE 

    Result: 

    OK 

    See step  3

  3. INSPECT FOG LIGHT BULB 
    1. Temporarily replace the front fog light bulb with a new or normally functioning one (Refer to PROCEDURE - Step 1 ).
    2. Check that the front fog light turn on.

      OK

      front fog light turn on.

    Result: 

    OK 

    END 

    Result: 

    NG 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (FRONT FOG LIGHT BULB - BATTERY) 
    GTY580789Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. for LH:
      1. Disconnect the A36 front fog light LH connector.
      2. Measure the voltage according to the value(s) in the table below.

        Standard Voltage

        Tester Connection Switch Condition Specified Condition
        A36-2 - Body ground Light control switch TAIL, front fog light switch ON 11 to 14 V
        Light control switch TAIL, front fog light switch OFF Below 1 V
      3. Reconnect the front fog light LH connector.
    2. for RH:
      1. Disconnect the A37 front fog light RH connector.
      2. Measure the voltage according to the value(s) in the table below.

        Standard Voltage

        Tester Connection Switch Condition Specified Condition
        A37-2 - Body ground Light control switch TAIL, front fog light switch ON 11 to 14 V
        Light control switch TAIL, front fog light switch OFF Below 1 V
      3. Reconnect the front fog light RH connector.

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FRONT FOG LIGHT BULB - BODY GROUND) 

    Result: 

    NG 

    See step  5

  5. INSPECT FOG LIGHT RELAY (FOG) 
    GTY215975Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the FOG 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 FOG relay.

    Result: 

    NG 

    REPLACE FOG RELAY 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (FOG RELAY - BATTERY, TAIL RELAY) 
    GTY538890Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the FOG relay from the engine room relay block.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      FOG relay terminal 1 - Body ground Light control switch TAIL 11 to 14 V
      FOG relay terminal 3 - Body ground Always 11 to 14 V
    3. Reinstall the FOG relay.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (FOG RELAY - FRONT FOG LIGHT BULB) 
    1. Remove the FOG relay from the engine room relay block.
      GTY570680Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. for LH:
      1. Disconnect the A36 front fog light LH connector.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        FOG relay terminal 5 - A36-2 Always Below 1 Ω
        FOG relay terminal 5 - Body ground Always 10 kΩ or higher
      3. Reconnect the front fog light LH connector.
    3. for RH:
      1. Disconnect the A37 front fog light RH connector.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        FOG relay terminal 5 - A37-2 Always Below 1 Ω
        FOG relay terminal 5 - Body ground Always 10 kΩ or higher
      3. Reconnect the front fog light RH connector.
    4. Reinstall the FOG relay.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (FOG RELAY - MAIN BODY ECU) 
    GTY603061Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the H4 main body ECU connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      H4-4 (FFGO) - Body ground Light control switch TAIL 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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