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Headlight Dimmer Switch Circuit [10/2015 - 08/2019]: Procedure

  1. READ VALUE USING TECHSTREAM 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Body Electrical / Main Body / Data List.
    5. Read the Data List according to the display on the Techstream.

      Body Electrical > Main Body > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Dimmer SW Dimmer switch high position signal ON or OFF ON: Dimmer switch in high or high flash position
      OFF: Dimmer switch in low position      		 -
      Passing Light SW Dimmer switch high flash position (pass) signal ON or OFF ON: Dimmer switch in high flash position
      OFF: Dimmer switch not in high flash position      		 -
      Front Fog Light SW Fog light switch front position signal ON or OFF ON: Fog light switch in front position
      OFF: Fog light switch off      		 -
      Auto Light SW Light control switch AUTO position signal ON or OFF ON: Light control switch in AUTO position
      OFF: Light control switch not in AUTO position      		 -
      Head Light SW (Head) Light control switch head position signal ON or OFF ON: Light control switch in head position
      OFF: Light control switch not in head position      		 -
      Head Light SW (Tail) Light control switch tail position signal ON or OFF ON: Light control switch in tail or head position
      OFF: Light control switch not in tail or head position      		 -

      Body Electrical > Main Body > Data List 

      Tester Display
      Dimmer SW
      Passing Light SW
      Front Fog Light SW
      Auto Light SW
      Head Light SW (Head)
      Head Light SW (Tail)

      OK

      Normal conditions listed above are displayed.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2015 - 12/2017]  , or refer to  PROBLEM SYMPTOMS TABLE [12/2017 - 03/2018]  , or refer to  PROBLEM SYMPTOMS TABLE [03/2018 - 08/2019] 

    Result: 

    NG 

    See step  2

  2. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY 

    HINT: 

    Inspect the items that did not change when reading the Data List.

    1. Remove the headlight dimmer switch assembly.

      Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 08/2019]

    2. Measure the resistance according to the value (s) in the table below.
      GTY642281Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Headlight Dimmer Switch Assembly)

      Standard Resistance

      LIGHT CONTROL SWITCH

      Tester Connection Condition Specified Condition
      18 (T) - 15 (EL) Light control switch off*1 or DRL OFF*2 10 kΩ or higher
      19 (H) - 15 (EL) Light control switch off*1 or DRL OFF*2 10 kΩ or higher
      20 (A) - 15 (EL) Light control switch off*1 or DRL OFF*2 10 kΩ or higher
      18 (T) - 15 (EL) Light control switch in tail position Below 1 Ω
      18 (T) - 15 (EL) Light control switch in head position Below 1 Ω
      19 (H) - 15 (EL) Light control switch in head position Below 1 Ω
      20 (A) - 15 (EL) Light control switch in AUTO position Below 1 Ω
      DIMMER SWITCH

      Tester Connection Condition Specified Condition
      16 (HL) - 15 (EL) Dimmer switch in low position Below 1 Ω
      14 (HU) - 15 (EL) Dimmer switch in high or high flash position Below 1 Ω
      17 (HF) - 15 (EL) Dimmer switch in high flash position Below 1 Ω
      FOG LIGHT SWITCH

      Tester Connection Condition Specified Condition
      9 (BFG) - 8 (LFG) Fog light switch off 10 kΩ or higher
      9 (BFG) - 8 (LFG) Fog light switch in front position Below 1 Ω
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY. Refer to  REMOVAL [10/2015 - 08/2016]  , or refer to  REMOVAL [08/2016 - 08/2019] 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER SWITCH ASSEMBLY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)) 
    1. Disconnect the J8 main body ECU (multiplex network body ECU) connector.
    2. Measure the resistance according to the value (s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      J28-9 (BFG) - J8-26 (FFOG) Always Below 1 Ω
      J28-14 (HU) - J8-24 (HU) Always Below 1 Ω
      J28-17 (HF) - J8-10 (HF) Always Below 1 Ω
      J28-18 (T) - J8-22 (TAIL) Always Below 1 Ω
      J28-19 (H) - J8-12 (HEAD) Always Below 1 Ω
      J28-20 (A) - J8-8 (A) Always Below 1 Ω
      J28-9 (BFG) or J8-26 (FFOG) - Body ground Always 10 kΩ or higher
      J28-14 (HU) or J8-24 (HU) - Body ground Always 10 kΩ or higher
      J28-17 (HF) or J8-10 (HF) - Body ground Always 10 kΩ or higher
      J28-18 (T) or J8-22 (TAIL) - Body ground Always 10 kΩ or higher
      J28-19 (H) or J8-12 (HEAD) - Body ground Always 10 kΩ or higher
      J28-20 (A) or J8-8 (A) - Body ground Always 10 kΩ or higher
      J28-15 (EL) - Body ground Always Below 1 Ω
      J28-8 (LFG) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2015 - 08/2016]  , or refer to  REMOVAL [08/2016 - 03/2018]  , or refer to  REMOVAL [03/2018 - 08/2019] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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