LIGHTING SYSTEM Headlight Signal Circuit

DESCRIPTION

Illumination of the low beam headlight is controlled by the main body ECU (instrument panel junction block assembly).

WIRING DIAGRAM

A004TI9E04

CAUTION / NOTICE / HINT

Note


  • Recognition code registration is necessary when replacing the main body ECU (instrument panel junction block assembly).

  • If the main body ECU (instrument panel junction block assembly) is replaced, refer to the Service Bulletin.

  • As the door control battery is installed between the vehicle battery and main body ECU (instrument panel junction block assembly), 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 (instrument panel junction block assembly) before performing this troubleshooting procedure.

Tech Tips

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS (HEADLIGHT RELAY)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / Main Body / Active Test / Headlight Relay.

    5. Check that the headlights (low) turn on/off.

      Main Body
      Tester Display Test Part Control Range Diagnostic Note
      Headlight Relay Headlight ON/OFF -
      OK
      Headlights (low) turn on/off.

    OK

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

    NG

  2. INSPECT H-LP RELAY


    1. Remove the H-LP relay from the engine room No. 1 relay block.

    2. Inspect the H-LP relay Click here.


    NG

    REPLACE H-LP RELAY

    OK

  3. CHECK HARNESS AND CONNECTOR (H-LP RELAY - BATTERY)

    A004OFRE02
    Text in Illustration
    *a

    Front view of wire harness connector

    (to H-LP Relay)

    1. Remove the H-LP relay from the engine room No. 1 relay block.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      H-LP relay terminal 2 - Body ground Always 11 to 14 V
      H-LP relay terminal 3 - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (H-LP RELAY - MAIN BODY ECU [INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY])


    1. Remove the H-LP relay from the engine room No. 1 relay block.

    2. Disconnect the D79 main body ECU (instrument panel junction block assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H-LP relay terminal 1 - D79-20 (HRLY) Always Below 1 Ω
      H-LP relay terminal 1 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (H-LP RELAY - HEADLIGHT ASSEMBLY LH)


    1. Remove the H-LP relay from the engine room No. 1 relay block.

    2. Disconnect the A75*1 or A77*2 front fog light assembly LH connector.


      • *1: for Halogen Headlight

      • *2: for LED Headlight

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

      Standard Resistance
      for Halogen Headlight
      Tester Connection Condition Specified Condition
      H-LP relay terminal 5 - A75-2 (LO) Always Below 1 Ω
      H-LP relay terminal 5 - Body ground Always 10 kΩ or higher
      for LED Headlight
      Tester Connection Condition Specified Condition
      H-LP relay terminal 5 - A77-4 (LO) Always Below 1 Ω
      H-LP relay terminal 5 - Body ground Always 10 kΩ or higher

    OK

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR