PRE-COLLISION SYSTEM(for Stereo Camera Type)


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    Object Recognition Camera

    • Obtains detection information for vehicles, pedestrians and bicycle riders to the front of the vehicle, and sends information to the driving support ECU assembly.

    • Operates the forward recognition hood with heater sub-assembly to remove condensation from the part of the windshield in front of the object recognition camera.
    Forward Recognition Hood with Heater Sub-assembly Heats the sheet heater in accordance with the signals from the object recognition camera.
    Millimeter Wave Radar Sensor Assembly Radiates millimeter waves forward, uses the reflected millimeter waves for detecting the presence of a vehicle ahead, the vehicle-to-vehicle distance, and the relative speed, and then transmits this information to the driving support ECU assembly.
    Front Side Radar Sensor Emits radar waves and detects the presence of other vehicles, the vehicle-to-vehicle distance and the relative vehicle speed, based on reflected radar waves.
    Blind Spot Monitor Sensor Emits radar waves and detects the presence of other vehicles, the vehicle-to-vehicle distance and the relative vehicle speed, based on reflected radar waves.
    Yawrate Sensor Detects the yaw rate and lateral/longitudinal deceleration of the vehicle and transmits the signal to the driving support ECU assembly.
    Steering Sensor Detects the steering direction and angle of the steering wheel and transmits the signal to the driving support ECU assembly.
    Speed Sensor Detects the wheel speed and transmits signals to the skid control ECU assembly.
    Ambient Temperature Sensor (Thermistor Assembly) Detects the ambient temperature and transmits signals to the air conditioning amplifier assembly.
    Steering Pad Switch Assembly Switches the display of multi-information display within combination meter assembly.
    Satellite Switch Set VSC OFF Switch Disables the pre-collision braking and pre-collision brake assist operation when the switch is turned on. The PCS warning light illuminates to show that the pre-collision braking and pre-collision brake assist operation is disabled. The pre-collision warning function can still operate.
    Stop Light Switch Assembly Detects the depressing of the brake pedal and transmits a signal to the skid control ECU assembly.
    No. 3 Semiconductor Power Integration ECU Illuminates the stop lights in accordance with the signals from the stop light switch assembly or skid control ECU assembly.
    Brake Actuator Assembly

    • Actuates the brakes in accordance with the signals from the skid control ECU assembly.

    • Detects the master cylinder pressure and transmits a signal to the skid control ECU assembly.

    • Detects the wheel cylinder pressure and transmits a signal to the skid control ECU assembly.
    Combination Meter Assembly PCS Warning Light

    • Flashes or illuminates to warn the driver in accordance with signals from the driving support ECU assembly.

    • Flashes when the pre-collision system is malfunctioning.

    • Illuminates when the pre-collision system is not available due to when the pre-collision system is turned OFF or pre-collision braking and pre-collision brake assist operation are disabled using the VSC OFF switch.
    VSC OFF Indicator Light Illuminates when in VSC OFF mode.
    Master Warning Light Illuminates to warn the driver in accordance with signals from the driving support ECU assembly when the pre-collision system is malfunctioning.
    Multi-information Display

    • Displays a warning message to inform or warn the driver of the system condition in accordance with signals from the driving support ECU assembly.

    • Displays the pre-collision system setting screen.
    Buzzer Sounds to warn the driver in accordance with signals from the driving support ECU assembly when the system is malfunctioning.
    Meter Mirror Sub-assembly

    • Displays a warning to warn the driver of the possibility of a collision with the detected object.

    • Displays an animation to call the driver's attention to a pedestrian in front of the vehicle.
    Multi Display Displays a warning to warn the driver of the possibility of a collision with the detected object.
    Driving Support ECU Assembly

    • Obtains information on vehicles, pedestrians and bicycle riders to the front of the vehicle from the millimeter wave radar sensor assembly, front side radar sensor and object recognition camera, and controls the pre-collision system.

    • Requests that the skid control ECU assembly performs pre-collision brake assist or brake control of the pre-collision brake when it is determined that there is a possibility or a high possibility of a collision.

    • Requests that the absorber control ECU performs damping force control of the shock absorber when it is determined that there is a high possibility of a collision.

    • Requests that the power steering ECU performs steering control when it is determined that there is a high possibility of a collision.

    • Requests that the seat belt control ECU operates the pre-collision seat belt when it is determined that there is a high possibility of a collision.

    • Requests that the position control ECU assembly performs seatback control when it is determined that there is a high possibility of a collision.
    Skid Control ECU Assembly

    • Receives a brake assist standby request signal from the driving support ECU assembly, and switches the brake assist to standby mode. When a master cylinder pressure signal is input, it activates the brake assist.

    • Receives a pre-collision brake request signal from the driving support ECU assembly, and then applies the brakes.

    • Transmits vehicle speed signals to the driving support ECU assembly.
    Hybrid Vehicle Control ECU

    • Transmits accelerator pedal position signal and shift position signal to the driving support ECU assembly.

    • Controls hybrid system output based on the signal from the driving support ECU assembly.
    Absorber Control ECU Controls the damping force based on the signals received from the driving support ECU assembly.
    Power Steering ECU Performs steering control according to signals from the driving support ECU assembly.
    FR Steering Control ECU*1

    • Controls the turning angle of the front wheels based on the signals received from the driving support ECU assembly.

    • Calculates the turning angle of the rear wheels and sends it to the RR steering control ECU.
    RR Steering Control ECU*1 Controls the turning angle of the rear wheels based on the signals received from the FR steering control ECU.
    Seat Belt Control ECU Operates the pre-collision seat belt according to signals from the driving support ECU assembly.
    Position Control ECU (Passenger Side) Performs seatback control for the front passenger seat based on signals from the driving support ECU assembly.
    RR Position Control ECU Assembly*2 Performs seatback control for the rear seat based on signals from the driving support ECU assembly.
    Airbag ECU Assembly Performs control determination based on signals from the driving support ECU assembly, and operates the side collision airbag when necessary.
    Pedestrian Detection ECU Assembly Operates the pop up hood according to signals from the driving support ECU assembly.
    Parking Assist ECU*3 Receives collision determination signals from the driving support ECU assembly, and outputs image signals to the radio receiver assembly and multi display.
    Air Conditioning Amplifier Assembly Transmits ambient temperature signals to the object recognition camera.
    Central Gateway ECU (Network Gateway ECU) Relays and transmits each CAN communication data signal.

    *1: Models with Lexus Dynamic Handling (LDH) system

    *2: Models with rear power seat system

    *3: Models with panoramic view monitor system

  2. SYSTEM CONTROL


    1. The forward pre-collision system and forward/front side pre-collision system both perform arbitration processing (logical OR) within the driving support ECU assembly, in order to operate common devices.

      B003H1BE01

    2. The driving support ECU assembly performs control as follows, based on the millimeter wave radar sensor assembly, object recognition camera, front side radar sensor and vehicle information signals.

      Control Function
      Intuitive Pedestrian Detection Alert When the driving support ECU assembly determines that there is a possibility of a collision with a pedestrian who has stopped or is moving in front of the vehicle, it displays a warning on the headup display to call the driver's attention.
      Forward Pre-collision System Pre-collision Warning When the system determines that the possibility of a frontal collision is high, the buzzer sounds intermittently and messages are displayed on the multi-information display in the combination meter assembly, headup display and multi display in order to alert the driver.
      Pre-collision Brake Assist When the system determines that the possibility of a frontal collision is high, the system applies greater braking force in relation to how strongly the brake pedal is depressed.
      Pre-collision Braking When the system determines that the possibility of a frontal collision is high, the system warns the driver. If the system determines that the possibility of a frontal collision is extremely high, the brakes are automatically applied to help avoid the collision or help reduce the collision speed.
      Adaptive Variable Suspension Control When the system determines that the possibility of a frontal collision is high, the damping force of the shock absorber is optimized to enhance vehicle response.
      Crash Avoidance Assist (CAA) Control* When the system determines that the possibility of a frontal collision is high, the steering gear ratio is changed by the Variable Gear Ratio Steering (VGRS) system when the driver performs steering operations, enhancing vehicle steering response. In addition, the Lexus Dynamic Handling (LDH) system controls the steering angle of the front and rear wheels, helping improve steering operation response and stability.
      Pre-collision Seat Belt Control When it is determined that there is a very high possibility of a collision, this uses a motor to wind the seat belt prior to the collision in order to increase the effectiveness of the pretensioner.
      Pre-collision Seat Back Control When it is determined that there is a very high possibility of a collision, this automatically controls power seats other than the driver seat.
      Pop Up Hood System-linked Control When it is determined that there is a very high possibility of a collision, this reduces the operation threshold for the pop up hood in order to increase its effectiveness.
      Forward/Front Side Pre-collision System Pre-collision Warning When the system determines that the possibility of a lateral collision is high, the buzzer sounds intermittently and messages are displayed on the multi-information display in the combination meter assembly, headup display and multi display in order to alert the driver.
      Pre-collision Brake Assist When the system determines that the possibility of a lateral collision is high, the system applies greater braking force in relation to how strongly the brake pedal is depressed.
      Pre-collision Seat Belt Control When it is determined that there is a very high possibility of a collision, this uses a motor to wind the seat belt prior to the collision in order to increase the effectiveness of the pretensioner.
      Side Collision Airbag-linked Control When it is determined that there is a very high possibility of a collision, this information is sent to the airbag ECU assembly. The airbag ECU assembly performs side collision airbag control determination based on this information. This increases the accuracy of control determination in an attempt to improve side collision airbag operation performance and effectiveness.
      Active Steering Avoidance Support When the driving support ECU assembly determines that there is a high possibility of a collision with a continuous structure (such as a guardrail) or a pedestrian within the vehicle lane, that it would be difficult to avoid the collision by controlling the brake, that it would be possible to avoid the collision by controlling steering and that there is enough space to avoid the collision, steering control is automatically performed.
      Front Cross Traffic Alert When the vehicle enters an intersection at a low speed, this detects the approach of crossing vehicles based on information from the front side radar sensor, and calls attention to the driver.

      *: Models with Lexus Dynamic Handling (LDH) system

  3. FUNCTION


    1. The pre-collision system is equipped with a function that can change the following settings.

      Pre-collision System

      • Pre-collision system on (activates) or off (does not activate) setting

      • Warning sensitivity level (Far, Middle or Near) setting*

      *: The warning sensitivity level of the pre-collision warning, intuitive pedestrian detection alert and front cross traffic alert changes at the same time.

      Intuitive Pedestrian Detection Alert and Front Cross Traffic Alert

      • Warning alert on (activates) or off (does not activate) setting*1

      • Warning sensitivity level (Far, Middle or Near) setting*2

      *1: The intuitive pedestrian detection alert and front cross traffic alert are turned on/off at the same time.

      *2: The warning sensitivity level of the pre-collision warning, intuitive pedestrian detection alert and front cross traffic alert changes at the same time.

      B003HBHC02
      *1

      Combination Meter Assembly


      • Multi-information Display

      		 *2 Steering Pad Switch Assembly

    2. When the pre-collision system is set to off, the PCS warning light illuminates. At that time, the multi-information display shows that the pre-collision system is off.

      B003GUHC01
      *1 Combination Meter Assembly *2 Steering Pad Switch Assembly
      *a Multi-information Display *b PCS Warning Light

      Tech Tips

      The system is automatically enabled each time the power switch is turned on (IG) or on (READY)

    3. The warning sensitivity level of the pre-collision system can be switched on the multi-information display setting screen.

      Tech Tips


      • The pre-collision system is set to Middle by default.

      • The selected warning sensitivity level is maintained even after the power switch is turned off.

  4. DIAGNOSIS


    1. Initial Check


      1. The driving support ECU assembly performs an initial check on the system for approximately 3 seconds after the power switch has been turned on (IG).

    2. Monitor Function


      1. After completing the initial check, the pre-collision system becomes ready to operate. During this time, the driving support ECU assembly periodically monitors the system for any malfunctions.

    3. Diagnostic Trouble Code (DTC)


      1. If the driving support ECU assembly detects a malfunction in the pre-collision system, it stores a Diagnostic Trouble Code (DTC) in memory.