LIGHTING SYSTEM Headlight Relay Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives headlight dimmer switch information signals, and illuminates the headlight.

WIRING DIAGRAM

A005LDAE02

CAUTION / NOTICE / HINT

Note


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

  • Initialization is necessary when the main body ECU (multiplex network body ECU) is replaced Click here.*


  • *: w/ Automatic Light Control System

PROCEDURE


  1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (HEADLIGHT RELAY)


    1. Using the intelligent tester, perform the Active Test Click here.

      Main Body
      Tester Display Test Part Control Range Diagnostic Note
      Headlight Relay Low beam headlight relay ON/OFF -
      OK
      Headlight relay operates (low beam headlights illuminate).
      Result
      Result Proceed to
      NG A
      OK B

    B

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

    A

  2. INSPECT HEADLIGHT RELAY (H-LP/US-DRL)


    1. Remove the headlight relay (H-LP/US-DRL) from the No. 2 engine room relay block.

    2. Inspect the headlight relay (H-LP/US-DRL) Click here.


    NG

    REPLACE HEADLIGHT RELAY (H-LP/US-DRL)

    OK

  3. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY - BATTERY)

    A005LEXE01
    Text in Illustration
    *1 No. 2 Engine Room Relay Block
    *a H-LP/US-DRL Relay Terminal

    1. Remove the headlight relay (H-LP/US-DRL) from the No. 2 engine room relay block.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      Relay terminal 1 - Body ground Always 11 to 14 V
      Relay terminal 5 - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY - INSTRUMENT PANEL JUNCTION BLOCK)


    1. Remove the headlight relay (H-LP/US-DRL) from the No. 2 engine room relay block.

    2. Disconnect the 3C instrument panel junction block assembly connector.

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

      A005J9QE02
      Text in Illustration
      *1 No. 2 Engine Room Relay Block - -
      *a H-LP/US-DRL Relay Terminal *b

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)
      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      Relay terminal 2 - 3C-18 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      3C-18 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY


    1. Remove the instrument panel junction block assembly Click here.

    2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

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

      A005HD4E02
      Text in Illustration
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      3C-18 - MB-15 (HRLY) Always Below 1 Ω

    OK

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

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here