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Home › Lexus › 2007 › RX 400h AWD › Repair and Diagnosis › Accessories & Equipment › Headlights › Lighting › Lighting System › Headlight Relay Circuit › Inspection Procedure

Inspection Procedure

  1. PERFORM ACTIVE TEST BY INTELLIGENT TESTER 
    1. Connect the intelligent tester to DLC3.
    2. Turn the ignition switch to ON position and press the intelligent tester main switch ON.
    3. Select the item below in the ACTIVE TEST and then check that the relay operates.

    BODY 

    BODY ITEM REFERENCE CHART

    Item Test Details Diagnostic Note
    HEAD LIGHT Turn Headlight relay ON/OFF -

    NG: GO TO step   2 

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

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    1. Disconnect the connector from the J/B No.2 (power distributor).
    2. Measure the voltage according to the value(s) in the table below.

    Voltage 

    TESTER CONNECTION SPECIFIED VALUE REFERENCE CHART

    Tester connection Condition Specified value
    2I-1 (+B) - Body ground Always 10 to 14 V

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 1: Disconnecting Connector From J/B No.2 (Power Distributor)
    G05273782Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  3. CHECK MODE MONITOR TERMINAL (H-LP R RELAY, H-LP L RELAY) 
    1. Preparation
      1. Connect the connector.
      2. Remove the cover of the fusible link block assembly.
      3. Set the vehicle to the following condition.
        • Ignition switch ON.
        • Headlight dimmer switch LO.
    2. Check voltage
      1. Measure the voltage between the Mode Monitor Terminal and body ground.

    Voltage 

    RESULT CHART

    Result Proceed to
    0 V or Approx. 12 V A
    Approx. 6.2 V B
    Approx. 2.0 V C

    B: GO TO step   5 

    C: GO TO step   9 

    Fig 2: Checking Mode Monitor Terminal (H-LP R Relay, H-LP L Relay)
    G05201886Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    A: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (J/B NO. 2 - MODE MONITOR TERMINAL) 
    1. Disconnect the connector from the J/B No.2.
    2. Measure the resistance according to the value(s) in the table below.

    Resistance 

    TESTER CONNECTION SPECIFIED VALUE REFERENCE CHART

    Tester connection Condition Specified value
    2G-5 - Mode monitor terminal Always Below 1 Ω
    2G-5 - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 3: Checking Harness And Connector (J/B No. 2 - Mode Monitor Terminal)
    G05280033Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  5. INSPECT JUNCTION BLOCK NO.2 (HEAD LIGHT RELAY) 
    1. Turn the ignition switch to OFF position.
    2. Remove the J/B No.2.
    3. Inspect the H-LP R.
      Fig 4: Inspecting Junction Block No. 2 (Head Light Relay)
      G05280034Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Connect the positive battery lead to terminal +B of the J/B No.2 and the negative lead to terminal SGND, PGND.
        SYMBOL CONNECTION REFERENCE CHART

        Symbols (terminals No.) Connection
        +B (2I-1) - SGND (2H-13), PGND (2F-1) Positive - Negative
      2. Measure the voltage according to the value(s) in the table below.

        Voltage 

        TESTER CONNECTION SPECIFIED CONDITION REFERENCE CHART

        Tester Connection Specified Condition
        LPR (2A-3) - Battery negative terminal Below 1 V
      3. Connect the battery negative lead to terminal HRLY of the J/B No.2.
        SYMBOL CONNECTION REFERENCE CHART

        Symbols (terminals No.) Connection
        HRLY (2H-8) Negative
      4. Measure the voltage according to the value(s) in the table below.

      Voltage 

      TESTER CONNECTION SPECIFIED CONDITION REFERENCE CHART

      Tester Connection Specified Condition
      LPR (2A-3) - Battery negative terminal 10 to 14 V
    4. Inspect the H-LP L.
    1. Connect the positive battery lead to terminal +B of the J/B No.2 and the negative lead to terminal SGND, PGND.
      SYMBOL CONNECTION REFERENCE CHART

      Symbols (terminals No.) Connection
      +B (2I-1) - SGND (2H-13), PGND (2F-1) Positive - Negative
    2. Measure the voltage according to the value(s) in the table below.

      Voltage 

      TESTER CONNECTION SPECIFIED CONDITION REFERENCE CHART

      Tester Connection Specified Condition
      LPL (2A-2) - Battery negative terminal Below 1 V
    3. Connect the battery negative lead to terminal HRLY of the J/B No.2.

      Voltage 

      SYMBOL CONNECTION REFERENCE CHART

      Symbols (terminals No.) Connection
      HRLY (2H-8) Negative
    4. Measure the voltage according to the value(s) in the table below.

    Voltage 

    TESTER CONNECTION SPECIFIED CONDITION REFERENCE CHART

    Tester Connection Specified Condition
    LPL (2A-2) - Battery negative terminal 10 to 14 V

    NG: REPLACE JUNCTION BLOCK NO.2 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (J/B NO. 2 - INSTRUMENT PANEL J/B) 
    1. Disconnect the connectors from the J/B No.2 (power distributor) and instrument panel J/B.
      Fig 5: Identifying J/B No. 2 And Instrument Panel J/B Connector Terminals
      G05280035Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

    Resistance 

    TESTER CONNECTION SPECIFIED VALUE REFERENCE CHART

    Tester connection Condition Specified value
    2H-8 (HRLY) - 1D-3 Always Below 1 Ω
    2H-8 (HRLY) - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  7. CHECK HARNESS AND CONNECTOR (J/B NO. 2 - HEADLIGHT ASSEMBLY) 
    1. Disconnect the connectors from the J/B No.2 (power distributor) and headlight assembly.
    2. Measure the resistance according to the value(s) in the table below.

    Resistance 

    TESTER CONNECTION SPECIFIED VALUE REFERENCE CHART

    Tester connection Condition Specified value
    2A-2 (LPL) - H5-2 (Headlight LH) Always Below 1 Ω
    2A-3 (LPR) - H9-2 (Headlight RH) Always Below 1 Ω
    2A-2 (LPL) - Body ground Always 10 kΩ or higher
    2A-3 (LPR) - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 6: Identifying J/B No. 2 And Headlight Assembly Connector Terminals
    G05280036Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  8. CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY - BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

    Resistance 

    TESTER CONNECTION SPECIFIED VALUE REFERENCE CHART

    Tester connection Condition Specified value
    H5-1 (Headlight LH) - Body ground Always Below 1 Ω
    H9-1 (Headlight RH) - Body ground Always Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 7: Identifying Headlight Assembly Connector Terminals
    G05280037Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

  9. CHECK HARNESS AND CONNECTOR (SHORT CIRCUIT DRIVEN SIDE BY RELAY) 
    1. Preparation
      1. For easier disconnection remove the J/B No.2 and then take apart the connectors.
      2. Disconnect only the connector "2A".
    2. Check voltage
      1. Measure the voltage between the Mode Monitor Terminal and body ground.

    Voltage 

    RESULT CHART

    Result Proceed to
    Approx. 6.2 V A
    Approx. 2.0 V B

    B: REPLACE JUNCTION BLOCK NO.2 

    Fig 8: Disconnecting 2A Connector
    G05273791Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    A: REPAIR OR REPLACE HARNESS OR CONNECTOR (SHORT CIRCUIT BETWEEN HEADLIGHT LO AND J/B NO.2) 

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