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Home >> Lexus >> 2008 >> IS 350 >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting >> Lighting System >> Headlight Relay Circuit >> Inspection Procedure

Inspection Procedure

  1. PERFORM ACTIVE TEST BY 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 / Body / Active Test.
    5. Check the operation.

      Body (Main Body ECU RH) 

      DIAGNOSTIC NOTE

      Tester Display Test Part Control Range Diagnostic Note
      Headlight Relay Headlight relay ON/OFF -

      OK: 

      Headlight assembly (low) illuminates. 

    NG: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN  PROBLEM SYMPTOMS TABLE  

    OK: Go to Next Step 

  2. INSPECT FUSE (H-LP L LWR, H-LP R LWR) 
    1. Remove the H-LP L LWR fuse from the engine room No. 2 relay block.
    2. Remove the H-LP R LWR fuse from the engine room No. 2 relay block.
    3. Measure the resistance of the fuses.

      Standard resistance: 

      Below 1 Ω 

    NG: REPLACE FUSE 

    OK: Go to Next Step 

  3. INSPECT HEAD LP RELAY 
    1. Remove the HEAD LP relay from the engine room No. 1 relay block.
    2. Measure the resistance according to the value (s) in the table below.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Specified Condition
      3 - 5 10 kΩ or higher
      3 - 5 Below 1 Ω (When battery voltage is applied to terminals 1 and 2)
      Fig 1: Head LP Relay Circuit Diagram
      G05832079Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE HEAD LP RELAY 

    OK: Go to Next Step 

  4. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - BATTERY) 
    1. Disconnect the RL main body ECU RH connector.
    2. Measure the voltage according to the value (s) in the table below.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      RL-7 (HRLY) - Body ground Always 10 to 14 V
      3. Fig 2: Identifying RL Main Body ECU RH Connector
      G05832080Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to Next Step 

  5. CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - BATTERY AND BODY GROUND) 
    1. Check the wire harness between the headlight (Low LH) and battery, and the headlight (Low LH) and body ground.
      1. Disconnect the B12 headlight connector.
      2. Measure the voltage and resistance according to the value (s) in the table below.

        Standard voltage 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        B12-17 (LO) - Body ground Turn the light control switch to the ON (HEAD) position. 10 to 14 V

        Standard resistance 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        B12-16 (E) - Body ground Always Below 1 Ω
        Fig 3: Identifying B12 Headlight Connector
        G05832081Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Check the wire harness between the headlight (Low RH) and battery, and the headlight (Low RH) and body ground.
      1. Disconnect the B2 headlight connector.
      2. Measure the voltage and resistance according to the value (s) in the table below.

        Standard voltage 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        B2-17 (LO) - Body ground Turn the light control switch to the ON (HEAD) position. 10 to 14 V

        Standard resistance 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        B2-16 (E) - Body ground Always Below 1 Ω
        Fig 4: Identifying B2 Headlight Connector
        G05832082Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: REPLACE HEADLIGHT ASSEMBLY (LOW LH OR LOW RH) 

    NG: Go to Next Step 

  6. CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - HEAD LP RELAY) 
    1. Check the harness and the connectors between the headlight (Low LH or Low RH) and the HEAD LP relay.
      1. Disconnect the B12 headlight connector.
      2. Remove the HEAD LP relay from the engine room No. 1 relay block.
      3. Measure the resistance according to the value (s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Headlight Assembly Tester Connection Specified Condition
        LH B12-17 (LO) - HEAD LP relay terminal (3) Below 1 Ω
        RH B2-17 (LO) - HEAD LP relay terminal (3) Below 1 Ω

        Standard resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Headlight Assembly Tester Connection Specified Condition
        LH B12-17 (LO) or HEAD LP relay terminal (3) - Body ground 10 kΩ or higher
        RH B2-17 (LO) or HEAD LP relay terminal (3) - Body ground 10 kΩ or higher
      Fig 5: Identifying Harness And Connector (Headlight (LOW LH Or LOW RH) - Head LP Relay)
      G05832083Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: REPLACE MAIN BODY ECU RH (COWL SIDE J/B RH) 

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