LIGHTING SYSTEM Headlight Dimmer Switch Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives light control switch signals, dimmer switch signals, fog light switch (front*1/rear*2) signals from the headlight dimmer switch.


WIRING DIAGRAM

B0057GAE03
B0057GAE04

CAUTION / NOTICE / HINT

Note


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

  • As the door control battery is installed between the vehicle battery and main body ECU (multiplex network body ECU), first perform the inspections in On-Vehicle Inspection to confirm that there are no malfunctions in the power source circuit for the main body ECU (multiplex network body ECU) before performing this troubleshooting procedure.*

    *: w/ Door Control Battery

PROCEDURE


  1. READ VALUE USING GTS (HEADLIGHT DIMMER SWITCH)


    1. Using the GTS, read the Data List.

      Click here


      Body Electrical > Main Body > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Dimmer SW Headlight dimmer switch (light control switch) high position signal ON or OFF

      ON: Headlight dimmer switch (light control switch) in high or high flash position

      OFF: Headlight dimmer switch (light control switch) in low position

      		 -
      Passing Light SW Headlight dimmer switch high flash position (pass) signal ON or OFF

      ON: Headlight dimmer switch in high flash position

      OFF: Headlight 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

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

      ON: Front fog light switch on

      OFF: Front fog light switch off

      		 w/ Front Fog Light
      Auto Light SW Headlight dimmer switch (light control switch) AUTO position signal ON or OFF

      ON: Headlight dimmer switch (light control switch) in AUTO position

      OFF: Headlight dimmer switch (light control switch) not in AUTO position

      		 -
      Head Light SW (Head) Headlight dimmer switch (light control switch) head position signal ON or OFF

      ON: Headlight dimmer switch (light control switch) in head position

      OFF: Headlight dimmer switch (light control switch) not in head position

      		 -
      Head Light SW (Tail) Headlight dimmer switch (light control switch) tail position signal ON or OFF

      ON: Headlight dimmer switch (light control switch) in tail or head position

      OFF: Headlight dimmer switch (light control switch) in neither tail nor head position

      		 -

      Body Electrical > Main Body > Data List
      Tester Display
      Dimmer SW
      Passing Light SW
      Rear Fog Light SW
      Front Fog Light SW
      Auto Light SW
      Head Light SW (Head)
      Head Light SW (Tail)
      Result
      Proceed to
      OK
      NG

    OK

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

    NG

  2. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY (LIGHT CONTROL SWITCH, DIMMER SWITCH)


    1. Remove the headlight dimmer switch assembly.

      Click here

    2. Inspect the headlight dimmer switch assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER SWITCH ASSEMBLY - MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU] AND BODY GROUND)


    1. Disconnect the I126*1 or I31*2 headlight dimmer switch assembly connector.

      *1: for LH Side Type

      *2: for RH Side Type

    2. Disconnect the I48 main body ECU (multiplex network body ECU) connector.

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

      Standard Resistance
      for LH Side Type
      Tester Connection Condition Specified Condition
      I48-22 (TAIL) - I126-18 (T) Always Below 1 Ω
      I48-12 (HEAD) - I126-19 (H) Always Below 1 Ω
      I48-8 (A) - I126-20 (A) Always Below 1 Ω
      I48-24 (HU) - I126-14 (HU) Always Below 1 Ω
      I48-10 (HF) - I126-17 (HF) Always Below 1 Ω
      I48-26 (FFOG) - I26-9 (BFG)*1 Always Below 1 Ω
      I48-23 (RFOG) - I126-7 (B)*2 Always Below 1 Ω
      I126-8 (LFG) - Body ground Always Below 1 Ω
      I126-15 (EL) - Body ground Always Below 1 Ω
      I48-22 (TAIL) - Body ground Always 10 kΩ or higher
      I48-12 (HEAD) - Body ground Always 10 kΩ or higher
      I48-8 (A) - Body ground Always 10 kΩ or higher
      I48-24 (HU) - Body ground Always 10 kΩ or higher
      I48-10 (HF) - Body ground Always 10 kΩ or higher
      I48-26 (FFOG) - Body ground*1 Always 10 kΩ or higher
      I48-23 (RFOG) - Body ground*2 Always 10 kΩ or higher
      *1: w/ Front Fog Light
      *2: w/ Rear Fog Light
      for RH Side Type
      Tester Connection Condition Specified Condition
      I48-22 (TAIL) - I31-13 (T) Always Below 1 Ω
      I48-12 (HEAD) - I31-12 (H) Always Below 1 Ω
      I48-8 (A) - I31-11 (A) Always Below 1 Ω
      I48-24 (HU) - I31-17 (HU) Always Below 1 Ω
      I48-10 (HF) - I31-14 (HF) Always Below 1 Ω
      I48-26 (FFOG) - I31-2 (BFG)*1 Always Below 1 Ω
      I48-23 (RFOG) - I31-4 (B)*2 Always Below 1 Ω
      I31-3 (LFG) - Body ground Always Below 1 Ω
      I31-16 (EL) - Body ground Always Below 1 Ω
      I48-22 (TAIL) - Body ground Always 10 kΩ or higher
      I48-12 (HEAD) - Body ground Always 10 kΩ or higher
      I48-8 (A) - Body ground Always 10 kΩ or higher
      I48-24 (HU) - Body ground Always 10 kΩ or higher
      I48-10 (HF) - Body ground Always 10 kΩ or higher
      I48-26 (FFOG) - Body ground*1 Always 10 kΩ or higher
      I48-23 (RFOG) - Body ground*2 Always 10 kΩ or higher
      *1: w/ Front Fog Light
      *2: w/ Rear Fog Light
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) for LHD: REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here
    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) for RHD: REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR