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Home >> Lexus >> 2015 >> IS 250 Base, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 48 (Adaptive Front-Lighting System - Diagnostics - Introduction) >> AFS (Adaptive Front-Lighting System) >> System Description [10/2017 - 09/2020] >> System Description [10/2017 - 09/2020]
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System Description [10/2017 - 09/2020]

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2020 Lexus IS 350, 2020 Lexus IS 300, 2019 Lexus IS 350, 2019 Lexus IS 300, and 2018 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.
  1. AUTOMATIC HEADLIGHT BEAM LEVEL CONTROL SYSTEM 
    1. General

      When the low beam headlights are on, the automatic headlight beam level control operates the headlight swivel motor in accordance with movement of the vehicle. The headlight swivel ECU assembly controls the system.

    2. Function of Main Components
      Component Outline
      Headlight Swivel ECU Assembly Receives various signals, calculates changes in the vehicle posture, and actuates the headlight swivel motor.
      Headlight Swivel Motor
      • Based on the signals received from the headlight swivel ECU assembly, the motors move the reflectors in the headlight to vary the low beam.
      • Uses a stepper motor to precisely regulate the angle of the projector.
      Rear Height Control Sensor Sub-assembly LH Transmits a height control sensor signal to the headlight swivel ECU assembly.
      Brake Actuator Assembly (Skid Control ECU) Transmits speed sensor signals (front LH and RH) to the headlight swivel ECU assembly.
      ECM Transmits an engine running status signal to the headlight swivel ECU assembly.
      Main Body ECU (Multiplex Network Body ECU) Transmits a headlight status signal.
      Combination Meter Assembly AFS OFF Indicator If the system malfunctions, the combination meter assembly alerts the driver by flashing the AFS OFF indicator light in accordance with the signal from the headlight swivel ECU assembly.
      Multi-information Display
      - AFS On/Off Switch
      • If the system malfunctions, a warning message will be displayed on the multi-information display in the combination meter assembly in accordance with the signal from the headlight swivel ECU assembly.
      • Turns the AFS (adaptive front-lighting system) on/off according to operation of the steering pad switch assembly.
  2. AFS (Adaptive Front-lighting System) 
    1. General

      An AFS (adaptive front-lighting system) is used in order to ensure a wide low beam lighting area and realize excellent visibility during turns by moving the low beam.

    2. Function of Main Components
      Component Outline
      Headlight Swivel ECU Assembly Receives various signals, calculates the target lighting angle, and actuates the headlight swivel motor.
      Headlight Swivel Motor
      • Driven by the headlight swivel ECU assembly, the motor moves the low beam left or right to the angle calculated by the headlight swivel ECU assembly.
      • Uses a stepper motor to precisely regulate the angle of the projector.
      Steering Sensor Detects the steering angle and direction and outputs signals to the headlight swivel ECU assembly.
      Rear Height Control Sensor Sub-assembly LH Transmits a height control sensor signal to the headlight swivel ECU assembly.
      Brake Actuator Assembly (Skid Control ECU) Transmits speed sensor signals (front LH and RH) to the headlight swivel ECU assembly.
      ECM
      • Transmits an engine running status signal to the headlight swivel ECU assembly.
      • Transmits a shift position signal to the headlight swivel ECU assembly. The headlight swivel ECU assembly determines whether the vehicle is being driven forward or backward based on this signal.
      Main Body ECU (Multiplex Network Body ECU) Transmits a headlight status signal.
      Combination Meter Assembly AFS OFF Indicator If the system malfunctions, the combination meter assembly alerts the driver by flashing the AFS OFF indicator light in accordance with the signal from the headlight swivel ECU assembly.
      Multi-information Display
      - AFS On/Off Switch
      • If the system malfunctions, a warning message will be displayed on the multi-information display in the combination meter assembly in accordance with the signal from the headlight swivel ECU assembly.
      • Turns the AFS (adaptive front-lighting system) on/off according to operation of the steering pad switch assembly.
    3. Low Speed Control
      1. The headlight swivel ECU assembly performs low speed control when all of the following conditions are met:
        • Engine is running.
        • Vehicle is being driven forward at a speed of 10 km/h (6 mph) or more.
        • Vehicle is being driven forward at a speed of less than 30 km/h (19 mph).
        • Steering angle is 6° or more.
        • Low beam headlights are on.
        • AFS (adaptive front-lighting system) is on.
      SWIVEL ANGLE RANGE

      Driving Condition Low Beam
      Left Right
      Right Turn 0° Fixed 0° to 10° to Right
      Left Turn 0° to 20° to Left 0° Fixed
    4. Medium-to-High Speed Control
      1. The headlight swivel ECU assembly performs medium-to-high speed control when all of the following conditions are met:
        • Engine is running.
        • Vehicle is being driven forward at a speed of 30 km/h (19 mph) or more.
        • Steering angle is 7.5° or more.
        • Low beam headlights are on.
        • AFS (adaptive front-lighting system) is on.
      SWIVEL ANGLE RANGE

      Driving Condition Low Beam
      Left Right
      Right Turn 0° to 5° to Right 0° to 10° to Right
      Left Turn 0° to 15° to Left 0° to 7.5° to Left
    5. Operation Stop Condition
      1. The headlight swivel ECU assembly stops performing control when any of the following conditions is met:
        • Engine is stopped.
        • Vehicle is being driven forward at a speed of less than 5 km/h (3 mph).
        • Steering angle is less than 7.5°.
        • Low beam headlights are off.
        • AFS (adaptive front-lighting system) is off.
        • Shift lever in R or N.
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