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Section 377 (Headlight & Taillight System): Inspection

WARNING: This page is about a different car, the 2003 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
  1. INSPECT LIGHT CONTROL SWITCH CONTINUITY 
    SWITCH SPECIFICATION

    Switch position Tester connection Specified condition
    OFF - No continuity
    TAIL 14-16 Continuity
    HEAD 13-14-16 Continuity
    Auto 12-16 Continuity

    If continuity is not as specified, replace the switch.

  2. INSPECT HEADLIGHT DIMMER SWITCH CONTINUITY 
    SWITCH SPECIFICATION

    Switch position Tester connection Specified condition
    Low beam 16-17 Continuity
    High beam 7-16 Continuity
    Flash 7-8-16 Continuity

    If continuity is not as specified, replace the switch.

    Fig 1: Identifying Connector
    G03375410Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Connector disconnected: INSPECT LIGHT CONTROL SWITCH CIRCUIT 

    Disconnect the connector from the switch and inspect the connector on the wire harness side, as shown.

    Fig 2: Identifying Connector On Wire Harness Side
    G03375411Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    SWITCH SPECIFICATION

    Tester connection Condition Specified condition
    13-Ground Always Battery positive voltage
    14-Ground Always Battery positive voltage

    If circuit is not as specified, inspect the wire harness.

  4. Connector disconnected: INSPECT HEADLIGHT DIMMER SWITCH CIRCUIT 

    Disconnect the connector from the switch and inspect the connector on the wire harness side, as shown.

    Fig 3: Identifying Connector On Wire Harness Side
    G03375412Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    TESTER CONNECTION

    Tester connection Condition Specified condition
    16-Ground Always Continuity
    8-Ground Always Battery positive voltage

    If circuit is not as specified, inspect the wire harness.

  5. Connector connected: INSPECT LIGHT CONTROL SWITCH CIRCUIT 

    Connect the wire harness side connector to the light control and dimmer switch and inspect the connector from the back side, as shown.

    Fig 4: Inspecting Connector From Back Side
    G03375413Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    TESTER CONNECTION

    Tester connection Condition Specified condition
    16-Ground Always Continuity
    13-Ground Light control switch OFF or TAIL Battery positive voltage
    13-Ground Light control switch HEAD No voltage
    14-Ground Light control switch OFF Battery positive voltage
    14-Ground Light control switch TAIL or HEAD No voltage

    If circuit is not as specified, inspect the wire harness.

  6. Connector connected: INSPECT HEADLIGHT DIMMER SWITCH CIRCUIT 

    Connect the wire harness side connector to the light control and dimmer switch and inspect the connector from the back side, as shown.

    Fig 5: Inspecting Connector From Back Side
    G03375414Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    TESTER CONNECTION

    Tester connection Condition Specified condition
    8 - Ground Headlight dimmer switch FLASH No voltage
    8 - Ground Headlight dimmer switch LOW or HIGH Battery positive voltage
    13-Ground Light control switch HEAD and dimmer switch LOW and fog light switch ON No voltage
    13-Ground Light control switch HEAD and dimmer switch HIGH or FLASH and fog light switch ON Battery positive voltage

    If circuit is not as specified, inspect the wire harness.

  7. INSPECT DAYTIME RUNNING LIGHT NO. 3 AND NO. 4 RELAY CONTINUITY 
    Fig 6: Inspecting Daytime Running Light Relay Continuity
    G03375415Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    TESTER CONNECTION

    Tester connection Condition Specified condition
    A1-B3 Always Continuity
    A3-A5 Always Continuity
    B3-B4 Always Continuity
    A2-A5 Apply battery positive voltage between terminals A1 and B3. Continuity
    B1-B2 Apply battery positive voltage between terminals B3 and B4. Continuity

    If continuity is not as specified, replace the relay.

  8. HEADLIGHT RELAY: INSPECT ENGINE ROOM R/B RELAY CIRCUIT (See  INSPECTION  ) 

    HINT:

    The headlight relay is built in the engine room junction block. Also, the relay is constructed with a relay block that is in the junction block as a unit. To disconnect the wire harness connecting with relay block is impossible. If the relay has a malfunction, replace it with junction block assembly wire harness together.

  9. INSPECT HEADLIGHT DIMMER (DAYTIME RUNNING LIGHT NO. 2) RELAY CIRCUIT (See  PROBLEM SYMPTOMS TABLE  ) 
    Fig 7: Inspecting Engine Room Relay Circuit
    G03375416Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  10. INSPECT TAILLIGHT CONTROL RELAY: INSPECT ENGINE ROOM R/B RELAY CIRCUIT (See  INSPECTION  ) 

    HINT:

    The taillight relay is built in engine room junction block. Also the relay is constructed with a relay block that is in the junction block as a unit. To disconnect the wire harness connecting with relay block is impossible. If the relay has a malfunction, replace it with junction block assembly wire harness together.

    Fig 8: Identifying Relay Is Built In Engine Room Junction Block
    G03375417Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  11. AUTO ON: INSPECT AUTOMATIC LIGHT CONTROL 
    1. Turn the ignition switch ON.
    2. Turn the light control switch to AUTO.
    3. Gradually cover the top of the sensor.
    4. Check the accessory lights and the headlights come on.
    Fig 9: Gradually Cover Top Of Sensor (ON)
    G03375418Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  12. AUTO OFF: INSPECT AUTOMATIC LIGHT CONTROL 
    1. Gradually uncover the sensor.
    2. Check the accessory lights and the headlights go off.
  13. INSPECT LIGHT-OFF CONDITION 
    1. Turn the ignition switch ON.
    2. Lights auto ON:

      Gradually cover the top of the sensor.

    3. Check that the lights go off under the following conditions.
      1. Light control switch is OFF.
      2. The area around the sensor gets light.
      3. The driver's door is opened with the ignition switch OFF.
    Fig 10: Gradually Cover Top Of Sensor (OFF)
    G03375419Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  14. INSPECT LIGHTS-ON CONDITION 
    1. Open the driver's door while the ignition switch is OFF.
    2. Turn the light control switch to AUTO as leaving the door open, and cover the top of the sensor to check that the lights comes on by corning the ignition switch to ON.
  15. Connector disconnected: INSPECT AUTOMATIC LIGHT CONTROL SENSOR CIRCUIT 

    Disconnect the connector from the sensor and inspect the connector on the wire harness side, as shown in the chart.

    HINT:

    • Ignition switch is ON.
    • Light control switch is in AUTO.
    • Around the vehicle is light.
    Fig 11: Identifying Wire Harness Side
    G03375420Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    TESTER CONNECTION

    Tester connection Condition Specified condition
    6 - Ground Always Continuity
    3 - Ground Close the driver's door again while the ignition switch OFF No voltage
    3 - Ground Ignition switch position ON 5.2-9.0V

    If circuit is as specified, perform the inspection below.

    If the circuits is not as specified, inspect the circuit connected to other parts.

  16. Connector connected: INSPECT AUTOMATIC LIGHT CONTROL SENSOR CIRCUIT 

    Connect the wire harness side connector to the sensor and inspect wire harness side connector from the back side, as shown.

    HINT:

    • Ignition switch is ON.
    • Light control switch is in AUTO
    • Around the vehicle is light.
    Fig 12: Inspecting Wire Harness Side Connector From Back Side
    G03375421Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    TESTER CONNECTION

    Tester connection Condition Specified condition
    4 - Ground (CLTS - Body ground) Always Pulse generation
    3 - Ground (CLTB - Body ground) Ignition switch ON 10-14V

    If circuit is as specified, inspect the circuit (See CIRCUIT INSPECTION ). If the circuits is not as specified, replace the sensor with a new one.

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