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Headlight Dimmer Switch Circuit (To 08/2009): Procedure

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

      Tester Display Measurement Item/Range Normal Condition
      Dimmer Hi SW Dimmer switch high position signal/ON or OFF ON: Dimmer switch in high or high flash (pass) position
      OFF: Dimmer switch in low position
      Passing Light SW Dimmer switch high flash (pass) position signal/ON or OFF ON: Dimmer switch in high flash (pass) position
      OFF: Dimmer switch not in high flash (pass) position
      Front Fog Light SW Front fog light switch signal/ON or OFF ON: Front fog light switch on
      OFF: Front fog light switch off
      Light Auto 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
      Headlight SW Light control switch head position signal/ON or OFF ON: Light control switch in head position
      OFF: Light control switch not in head position
      Taillight SW Light control switch tail position signal/ON or OFF ON: Light control switch in tail or head position
      OFF: Light control switch in neither tail nor head position

      OK

      Normal conditions listed above are displayed.

    NG → See step   2 

    OK → See step   4 

  2. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY 

    HINT: 

    Inspect the items that did not change as a result of monitoring the Data List.

    1. Remove the headlight dimmer switch assembly. Refer to COMPONENTS .
      Fig 1: Identifying Headlight Dimmer Switch Connector Terminals
      GTY275331Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      LIGHT CONTROL SWITCH

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

      Tester Connection Switch Condition Specified Condition
      11 (HU) - 12 (EL) Dimmer switch in low position 10 kΩ or higher
      11 (HU) - 12 (EL) Dimmer switch in high position Below 1 Ω
      12 (EL) - 17 (HF) Dimmer switch in high flash position Below 1 Ω
      FOG LIGHT SWITCH

      Tester Connection Switch Condition Specified Condition
      3 (LFG) - 4 (BFG) Fog light switch off 10 kΩ or higher
      3 (LFG) - 4 (BFG) Fog light switch on Below 1 Ω

      OK

      Headlight dimmer switch assembly is normal.

      TEXT IN ILLUSTRATION

      *1 Component without harness connected
      (Headlight Dimmer Switch Assembly)

    NG → See step   5 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - HEADLIGHT DIMMER SWITCH ASSEMBLY) 
    1. Disconnect the F39 headlight dimmer switch assembly connector.
      Fig 2: Identifying F39 Headlight Dimmer Switch Assembly & F13 Main Body ECU (Multiplex Network Body ECU) Connectors
      GTY274889Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the F13 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
      F39-4 (BFG) - F13-27 (FFOG) Always Below 1 Ω
      F39-11 (HU) - F13-5 (HU) Always Below 1 Ω
      F39-17 (HF) - F13-8 (HF) Always Below 1 Ω
      F39-18 (T) - F13-30 (TAIL) Always Below 1 Ω
      F39-19 (A) - F13-28 (A) Always Below 1 Ω
      F39-20 (H) - F13-29 (HEAD) Always Below 1 Ω
      F39-4 (BFG) - Body ground Always 10 kΩ or higher
      F39-11 (HU) - Body ground Always 10 kΩ or higher
      F39-17 (HF) - Body ground Always 10 kΩ or higher
      F39-18 (T) - Body ground Always 10 kΩ or higher
      F39-19 (A) - Body ground Always 10 kΩ or higher
      F39-20 (H) - Body ground Always 10 kΩ or higher
      F39-12 (EL) - Body ground Always Below 1 Ω
      F39-3 (LFG) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Headlight Dimmer Switch Assembly)
      *2 Front view of wire harness connector
      (to Main Body ECU (Multiplex Network Body ECU))

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   6 

  4. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
  5. REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY. Refer to  COMPONENTS 
  6. REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  COMPONENTS 
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