LIGHTING SYSTEM Headlight Dimmer Switch Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives the following switch information:


WIRING DIAGRAM

A0004X4E34

CAUTION / NOTICE / HINT

Note

If the main body ECU (multiplex network body ECU) is replaced, refer to Service Bulletin.

PROCEDURE


  1. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / Main Body / Data List.

    5. Read the display on the GTS.

      Main Body
      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

      		 -
      Rear Fog Light SW Rear fog light switch signal/ON or OFF

      ON: Rear fog light switch on

      OFF: Rear fog light switch off

      		 -
      Front Fog Light SW Front fog light switch signal/ON or OFF

      ON: Front fog light switch on

      OFF: Front 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 in neither tail nor head position

      		 -
      OK
      Normal conditions listed above are displayed.

    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

  2. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY

    Tech Tips

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


    1. Remove the headlight dimmer switch assembly Click here.

    2. A0007MWE12
      Text in Illustration
      *a

      Component without harness connected

      (Headlight Dimmer Switch Assembly)

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Light Control Switch
      Tester Connection Condition Specified Condition
      18 (T) - 15 (EL) Light control switch off 10 kΩ or higher
      19 (H) - 15 (EL) Light control switch off 10 kΩ or higher
      20 (A) - 15 (EL) Light control switch off 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
      14 (HU) - 15 (EL) Dimmer switch in low position 10 kΩ or higher
      14 (HU) - 15 (EL) Dimmer switch in high position Below 1 Ω
      14 (HU) - 15 (EL) Dimmer switch in high flash position Below 1 Ω
      17 (HF) - 15 (EL) Dimmer switch in high flash position Below 1 Ω
      Front Fog Light Switch
      Tester Connection Condition Specified Condition
      9 (BFG) - 8 (LFG) Front fog light switch off 10 kΩ or higher
      9 (BFG) - 8 (LFG) Front fog light switch on Below 1 Ω
      Rear Fog Light Switch
      Tester Connection Condition Specified Condition
      7 (B) - 8 (LFG) Rear fog light switch off 10 kΩ or higher
      7 (B) - 8 (LFG) Rear fog light switch on Below 1 Ω

    NG

    REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - HEADLIGHT DIMMER SWITCH ASSEMBLY)


    1. Disconnect the H10 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
      H19-9 (BFG) - H10-27 (FFOG) Always Below 1 Ω
      H19-7 (B) - H10-1 (RFOG) Always Below 1 Ω
      H19-14 (HU) - H10-5 (HU) Always Below 1 Ω
      H19-17 (HF) - H10-8 (HF) Always Below 1 Ω
      H19-18 (T) - H10-30 (TAIL) Always Below 1 Ω
      H19-19 (H) - H10-29 (HEAD) Always Below 1 Ω
      H19-20 (A) - H10-28 (A) Always Below 1 Ω
      H19-9 (BFG) - Body ground Always 10 kΩ or higher
      H19-7 (B) - Body ground Always 10 kΩ or higher
      H19-14 (HU) - Body ground Always 10 kΩ or higher
      H19-17 (HF) - Body ground Always 10 kΩ or higher
      H19-18 (T) - Body ground Always 10 kΩ or higher
      H19-19 (H) - Body ground Always 10 kΩ or higher
      H19-20 (A) - Body ground Always 10 kΩ or higher
      H19-15 (EL) - Body ground Always Below 1 Ω
      H19-8 (LFG) - Body ground Always Below 1 Ω

    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR