LIGHTING SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS


    1. Automatic Light Control System

      Component Function
      Headlight Dimmer Switch Assembly Light Control Switch The light control switch transmits an AUTO position signal to the driver side junction block assembly.
      Automatic Light Control Sensor

      - The automatic light control sensor receives various signals and illuminates the headlights, taillights, front position lights, and license plate lights.

      - The automatic light control sensor detects the ambient light level.

    2. HID Headlight System

      Component Function
      Driver Side Junction Block Assembly No. 1 Integration Relay The driver side junction block assembly receives the HEAD position signal and transmits a signal to the light control ECU.
      Headlight Dimmer Switch Assembly Light Control Switch The light control switch transmits a HEAD position signal to the driver side junction block assembly.
      Headlight Unit Light Control ECU The light control ECU transforms battery voltage to a high voltage of up to 25000 V and applies it to the discharge bulbs in order to illuminate them.
      Discharge Bulb The discharge bulb light shines ahead over a broader area and further forward, increasing the area visible to the driver.

    3. Automatic Headlight Beam Level Control System

      Component Function
      Headlight Leveling ECU Assembly The headlight leveling ECU assembly receives various signals, calculates the target lighting angle, and actuates the actuator.
      Headlight Unit Actuator

      • Based on the signals received from the headlight leveling ECU assembly, the actuators move the reflectors in the headlights.

      • Uses a step actuator to precisely regulate the angle of the reflectors.
      Rear Height Control Sensor Sub-assembly Detects the height of the vehicle.
      Driver Side Junction Block Assembly No. 1 Integration Relay Transmits the headlight status signal.
      Combination Meter Assembly

      • If the system malfunctions, the meter ECU alerts the driver by illuminates the headlight beam level control system warning light in accordance with the signal from the headlight leveling ECU assembly.

      • Transmits the vehicle speed signal to headlight leveling ECU assembly.

    4. Manual Headlight Beam Level Control System

      Component Function
      Headlight Leveling Switch The level of the headlight can be adjusted between 0 and 5, and a switch level status signal is sent to the actuator.
      Headlight Unit Actuator Actuates in accordance with signals from the headlight leveling switch and moves the reflector up and down.

  2. FUNCTION


    1. Automatic Light Control System


      1. When the light control switch is in the AUTO position, the automatic light control sensor detects the ambient light level and automatically turns the headlights, taillights, clearance lights, and license plate lights on or off accordingly.

      2. This system is controlled by the automatic light control sensor.

    2. Light Automatic Turn-off System


      1. The light automatic turn-off system is controlled by the automatic light control sensor.

      2. This system has the following functions:

        Switch Position Outline
        TAIL HEAD AUTO
        - - ○ While the lights (headlights, front position lights, front fog lights and taillights) are turned on, this system automatically turns them off when the ignition switch is turned off and the driver's door is opened.

    3. HID Headlight System


      1. The HID headlight system consists of discharge bulbs and light control ECUs.

      2. Light control ECU transforms the voltage that is input from the battery to a high voltage of up to 25000 V and applies it to the discharge bulbs in order to illuminate them.

      3. A fail-safe function is provided as a countermeasure against the high voltage generated when a problem occurs in the headlight system.

    4. Automatic Headlight Beam Level Control System


      1. The automatic headlight beam level control system mainly consists of a headlight leveling ECU assembly, rear height control sensor sub-assembly and two actuators.

      2. The headlight leveling ECU assembly calculates changes in the vehicle posture based on the signals from the rear height control sensor sub-assembly.

      3. Following this, the ECU controls the actuator based on this information, in order to change the headlight reflector angle.

      4. Initial Set Control

        When the engine is started, the headlight leveling ECU assembly drives the actuator, moves the headlight reflector to the lower limit position and returns it to the proper position. In this way, the headlight leveling ECU assembly assesses the position of the headlight for reference control.

  3. CONSTRUCTION


    1. HID Headlight System


      1. Discharge Bulb

        Instead of the filament contained in an incandescent bulb, a discharge bulb contains an arc tube, which is filled with xenon gas, and metal halide.

        A01J2M4E01
        Text in Illustration
        *1 Arc Tube *2 Lead Wire
        *3 Ceramic Pipe - -

      2. Discharge bulbs have the following advantages:


        • The light emitted by the bulb is close in color to sunlight. The light shines ahead over a broader area and further forward, increasing the area visible to the driver.

        • Less power is consumed.

  4. FAIL-SAFE


    1. HID Headlight System


      1. The light control ECU executes the fail-safe actions listed below in accordance with the problem that has been detected:

        Problem Outline
        Detection of Abnormal Input Voltage If the voltage input to the light control ECU deviates from the normal operating voltage (10 V to 16 V), the light control ECU stops illuminating the headlights. It resumes illuminating the headlights once the voltage reverts to the operating voltage range. However, if the input voltage decreases after the headlights have illuminated, the headlights will remain illuminated until the input voltage is insufficient to light the bulbs.
        Detection of Abnormal Output (Open Circuit or Short Circuit) If an abnormal condition (open or short) occurs in the voltage that is output by the light control ECU, the light control ECU stops illuminating the headlights and will maintain this state until the power is reinstated. Power is reinstated by turning the light control switch from off to on.
        Detection of Bulb Open If a bulb has not been inserted into the socket, the light control ECU stops producing a high voltage 1 second after the power has been turned on. The light control ECU will maintain this state until a bulb is correctly inserted and the power is reinstated by turning the light control switch from off to on.

    2. Automatic Headlight Beam Level Control System


      1. If the headlight leveling ECU assembly detects a malfunction in the automatic headlight beam level control system, it will take the actions indicated in the table below:

        Trouble Area Condition (Fail-safe Control for Automatic Headlight Beam Level Control) Automatic Headlight Beam Level Control System Warning Light
        Height Control Sensor Signal Malfunction

        • Stops the operation after returning to initial position (fails at higher than initial position).

        • Stops the operation in current condition (fails at lower than initial position).

        		 Blinks

  5. DIAGNOSIS


    1. Automatic Headlight Beam Level Control System


      1. If the headlight leveling ECU assembly detects a malfunction in the automatic headlight beam level control system, the headlight leveling ECU assembly blinks the automatic headlight beam level control system warning light. At the same time, the Diagnostic Trouble Codes (DTCs) are stored in memory. The DTCs can be read by use of the intelligent tester II. For details, refer to the corresponding Repair Manual for this model.