PRE-COLLISION SYSTEM


  1. FUNCTION OF MAIN COMPONENTS

    Item Function
    Millimeter Wave Radar Sensor Assembly Radiates millimeter wave radar 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.
    Forward Recognition Camera

    • Captures images of the area in front of the vehicle and processes them to detect vehicles or pedestrians*1 and sends information to the driving support ECU assembly.

    • Operates the camera heater to prevent condensation on windshield in front of the forward recognition camera.
    Driving Support ECU Assembly Determines whether a collision is imminent based on the information received from the sensors. It then outputs a brake assist standby request signal and pre-collision brake request signal if required.
    Forward Recognition Hood Sub-assembly with Heater (Camera Heater) Heats the sheet heater in accordance with the current from the forward recognition camera.
    Brake Actuator Assembly Master Cylinder Pressure Sensor Detects the master cylinder pressure and transmits a signal to the skid control ECU.
    Pump Motor Receives an operation signal from the skid control ECU and generates hydraulic pressure for brake control.
    Skid Control ECU

    • 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 and stop light signal to the driving support ECU assembly.
    Speed Sensors Detect the wheel speed of each of the 4 wheels and transmits the signals to the skid control ECU.
    Yawrate Sensor Detects the yaw rate and lateral/longitudinal deceleration of the vehicle and transmits the signal to the skid control ECU and the driving support ECU assembly.
    Steering Sensor Detects the angle and direction of steering and transmits a signal to the skid control ECU and the driving support ECU assembly.
    ECM

    • Detects the shift position signal and accelerator pedal opening angle and sends that information to the driving support ECU assembly.

    • Performs engine output control based on information from the driving support ECU assembly.
    Semiconductor PWR Integration ECU Stop Light Control Relay Receives a stop light turn on request signal from the skid control ECU, and turns on the stop lights.
    Stop Light Switch Assembly Detects if the brake pedal is depressed and transmits a signal to the skid control ECU.
    Stop Light Relay (Semiconductor Power Integration ECU) Receives a pre-collision braking control operation signal from the skid control ECU and illuminates the stop lights.
    Combination Switch Assembly VSC OFF Switch Disables the pre-collision brake and pre-collision brake assist operation when VSC OFF mode.
    Combination Meter Assembly PCS Warning Light

    • Illuminates to warn the driver in accordance with signals from the driving support ECU assembly.

    • Illuminates when the system is malfunctioning or temporarily disabled.

    • Illuminates when the pre-collision system is disabled.

    • Illuminates when pre-collision brake and pre-collision brake assist operation is disabled.
    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.

    • Disables the pre-collision system operation when selected PCS OFF mode in setting display function.

    • Changing the pre-collision warning timing when selected Far/Middle/Near in setting display function.
    Master Warning Light Illuminates to warn the driver in accordance with signals from the driving support ECU assembly.
    Skid Control Buzzer Sounds to warn the driver in accordance with signals from the driving support ECU assembly.
    Main Body ECU (Multiplex Network Body ECU) Outputs the specification signal of the vehicle to driving support ECU.
    Network Gateway ECU Transmits the signal between the CAN communication bus.
    Absorber Control ECU*2 Receives an Adaptive Variable Suspension system (AVS) operation request signal from the driving support ECU assembly and operates the linear solenoid.
    Front Steering Control ECU*3 Controls the gear ratio of the steering actuator assembly to perform appropriate evasion support in accordance with the operation request from the driving support ECU assembly.
    Rear Steering Control ECU*3 Controls the rear steering link assembly to perform appropriate evasion support in accordance with the operation request from the front steering control ECU.

    *1: Depending on the region in which the vehicle was sold, the pedestrian detection function may not be available.

    *2: Models with adaptive variable suspension system

    *3: Models with Lexus dynamic handling system

  2. FUNCTION


    1. PCS (Pre-Collision System)


      1. The pre-collision system uses a radar sensor and camera sensor to detect vehicles and pedestrians* in front of your vehicle. When the system determines that the possibility of a frontal collision with a vehicle or pedestrian is high, a warning operates to urge the driver to take evasive action and the potential brake pressure is increased to help the driver avoid the collision. If the system determines that the possibility of a frontal collision with a vehicle or pedestrian is extremely high, the brakes are automatically applied to help avoid the collision or help reduce the impact of the collision.

        *: Depending on the region in which the vehicle was sold, the pedestrian detection function may not be available. See the following table for details.

        Countries/areas Function availability Regions

        Europe*1,*2

        Australia

        New Zealand

        The Near and Middle East*3

        		 The pedestrian detection function is available. Region A

        Russia

        Ukraine

        South Africa

        Thailand

        Jordan

        Lebanon

        China

        Taiwan

        		 The pedestrian detection function is not available. Region B

        *1: Destination package for Canary Islands is included

        *2: Except destination packages for Russia and Ukraine

        *3: Except destination packages for Jordan and Lebanon

        Tech Tips

        The pre-collision system can be disabled/enabled and the warning timing can be changed.

    2. Pre-collision warning


      1. When the system determines that the possibility of a frontal collision is high, a buzzer will sound and a warning message will be displayed on the multi-information display to urge the driver to take evasive action.

    3. Pre-collision brake assist


      1. 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.

    4. Pre-collision braking


      1. 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 reduce the collision speed.

    5. Suspension control (Models with Adaptive Variable Suspension System)


      1. When the system determines that the possibility of a frontal collision is high, the Adaptive Variable Suspension System will control the damping force of the shock absorbers to help maintain an appropriate vehicle posture.

    6. Steering control (Models with Lexus Dynamic Handling System)


      1. When the system determines that the possibility of a frontal collision is high and the driver is operating the steering wheel, the LDH system will control the turning angle of the front and rear wheels and effort necessary to turn the steering wheel to help enhance steering responsiveness.

  3. OPERATING CONDITION


    1. Availability of the pedestrian detection function depends on the region in which the vehicle was sold. Read the following for details:

    2. Region A

      (The Pedestrian detection function is available)


      1. The pre-collision system is enabled and the system determines that the possibility of a frontal collision with a vehicle or pedestrian is high.

      2. Each function is operational at the following speeds:


          Pre-collision warning:

        • Vehicle speed is between approximately 7 and 110 mph (10 and 180 km/h). (For detecting a pedestrian, vehicle speed is between approximately 7 and 50 mph [10 and 80 km/h].)

        • The relative speed between your vehicle and the vehicle or pedestrian ahead is approximately 7 mph (10 km/h) or more.


          Pre-collision brake assist:

        • Vehicle speed is between approximately 20 and 110 mph (30 and 180 km/h). (For detecting a pedestrian, vehicle speed is between approximately 20 and 50 mph [30 and 80 km/h].)

        • The relative speed between your vehicle and the vehicle or pedestrian ahead is approximately 20 mph (30 km/h) or more.


          Pre-collision braking:

        • Vehicle speed is between approximately 7 and 110 mph (10 and 180 km/h). (For detecting a pedestrian, vehicle speed is between approximately 7 and 50 mph [10 and 80 km/h].)

        • The relative speed between your vehicle and the vehicle or pedestrian ahead is approximately 7 mph (10 km/h) or more.

        The system may not operate in the following situations:


        • If a battery terminal has been disconnected and reconnected and then the vehicle has not been driven for a certain amount of time.

        • If the shift lever is in R.

        • If VSC is disabled (only the pre-collision warning function will be operational).

    3. Region B

      (The pedestrian detection function is not available)


      1. The pre-collision system is enabled and the system determines that the possibility of a frontal collision with a vehicle is high.

      2. Each function is operational at the following speeds:


          Pre-collision warning:

        • Vehicle speed is between approximately 10 and 110 mph (15 and 180 km/h).

        • The relative speed between your vehicle and the vehicle ahead is approximately 7 mph (10 km/h) or more.


          Pre-collision brake assist:

        • Vehicle speed is between approximately 20 and 110 mph (30 and 180 km/h).

        • The relative speed between your vehicle and the vehicle ahead is approximately 20 mph (30 km/h) or more.


          Pre-collision braking:

        • Vehicle speed is between approximately 10 and 110 mph (15 and 180 km/h).

        • The relative speed between your vehicle and the vehicle ahead is approximately 7 mph (10 km/h) or more.

        The system may not operate in the following situations:


        • If a battery terminal has been disconnected and reconnected and then the vehicle has not been driven for a certain amount of time.

        • If the shift lever is in R.

        • If VSC is disabled (only the pre-collision warning function will be operational).

    4. Pedestrian detection function*


      1. The pre-collision system detects pedestrians based on the size, profile, and motion of a detected object. However, a pedestrian may not be detected depending on the surrounding brightness and the motion, posture, and angle of the detected object, preventing the system from operating properly.

        *: For countries/areas specified as Region B, the pedestrian detection function may not be available.

        B0072IP

    5. Cancelation of the pre-collision braking


      1. If either of the following occur while the pre-collision braking function is operating, it will be canceled:


        • The accelerator pedal is depressed strongly.

        • The steering wheel is turned sharply or abruptly.

    6. Conditions under which the system may operate even if there is no possibility of a collision


      1. In some situations such as the following, the system may determine that there is a possibility of a frontal collision and operate.


        • When passing a vehicle or pedestrian*.

        • When changing lanes while overtaking a preceding vehicle.

        • When overtaking a preceding vehicle that is changing lanes.

        • When overtaking a preceding vehicle that is making a left/right turn.

          B0072C3

        • When passing a vehicle in an oncoming lane that is stopped to make a right/left turn.

          B0072EJ

        • When driving on a road where relative location to vehicle ahead in an adjacent lane may change, such as on a winding road.

          B007268

        • When rapidly closing on a vehicle ahead.

        • If the front of the vehicle is raised or lowered, such as when the road surface is uneven or undulating.

        • When approaching objects on the roadside, such as guardrails, utility poles, trees, or walls.

        • When there is a vehicle, pedestrian*, or object by the roadside at the entrance of a curve.

          B00727B

        • When driving on a narrow path surrounded by a structure, such as in a tunnel or on an iron bridge.

        • When there is a metal object (manhole cover, steel plate, etc.), steps, or a protrusion on the road surface or roadside.

        • When a crossing pedestrian approaches very close to the vehicle*.

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        • When passing through a place with a low structure above the road (low ceiling, traffic sign, etc.).

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        • When passing under an object (billboard, etc.) at the top of an uphill road.

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        • When rapidly closing on an electric toll gate barrier, parking area barrier, or other barrier that opens and closes.

        • When using an automatic car wash.

        • When driving through or under objects that may contact the vehicle, such as thick grass, tree branches, or a banner.

          B0072AD

        • When the vehicle is hit by water, snow, dust, etc. from a vehicle ahead.

        • When driving through steam or smoke.

        • When there are patterns or paint on the road or a wall that may be mistaken for a vehicle or pedestrian*.

        • When driving near an object that reflects radio waves, such as a large truck or guardrail.

        • When driving near a TV tower, broadcasting station, electric power plant, or other location where strong radio waves or electrical noise may be present.

        *: For countries/areas specified as Region B, the pedestrian detection function may not be available.

    7. Situations in which the system may not operate properly


      1. In some situations such as the following, a vehicle may not be detected by the radar sensor and camera sensor, preventing the system from operating properly:


        • If an oncoming vehicle is approaching your vehicle.

        • If a vehicle ahead is a motorcycle or bicycle.

        • When approaching the side or front of a vehicle.

        • If a preceding vehicle has a small rear end, such as an unloaded truck.

        • If a preceding vehicle has a low rear end, such as a low bed trailer.

          B0072FX

        • If a vehicle ahead is carrying a load which protrudes past its rear bumper.

        • If a vehicle ahead has extremely high ground clearance.

          B007287

        • If a vehicle ahead is irregularly shaped, such as a tractor or side car.

        • If the sun or other light is shining directly on a vehicle ahead.

        • If a vehicle cuts in front of your vehicle or emerges from beside a vehicle.

        • If a vehicle ahead makes an abrupt maneuver (such as sudden swerving, acceleration or deceleration).

        • When suddenly cutting behind a preceding vehicle.

        • When a vehicle ahead is not directly in front of your vehicle.

          B0072KF

        • When driving in inclement weather such as heavy rain, fog, snow or a sandstorm.

        • When the vehicle is hit by water, snow, dust, etc. from a vehicle ahead.

        • When driving through steam or smoke.

        • When driving in a place where the surrounding brightness changes suddenly, such as at the entrance or exit of a tunnel.

        • When a very bright light, such as the sun or the headlights of oncoming traffic, shines directly into the camera sensor.

        • When the surrounding area is dim, such as at dawn or dusk, or while at night or in a tunnel.

        • After the engine has started the vehicle has not been driven for a certain amount of time.

        • While making a left/right turn and for a few seconds after making a left/right turn.

        • While driving on a curve and for a few seconds after driving on a curve.

        • If your vehicle is skidding.

        • If the front of the vehicle is raised or lowered.

          B007270

        • If the wheels are misaligned.

        • If a wiper blade is blocking the camera sensor.

        • The vehicle is wobbling.

        • The vehicle is being driven at extremely high speeds.

        • When driving on a hill.

        • If the radar sensor or camera sensor is misaligned.

      2. In some situations such as the following, sufficient braking force may not be obtained, preventing the system from performing properly:


        • If the braking functions cannot operate to their full extent, such as when the brake parts are extremely cold, extremely hot, or wet.

        • If the vehicle is not properly maintained (brakes or tires are excessively worn, improper tire inflation pressure, etc.).

        • When the vehicle is being driven on a gravel road or other slippery surface.

      3. Some pedestrians such as the following may not be detected by the radar sensor and camera sensor, preventing the system from operating properly*:


        • Pedestrians shorter than approximately 3.2 ft. (1 m) or taller than approximately 6.5 ft. (2 m).

        • Pedestrians wearing oversized clothing (a rain coat, long skirt, etc.), making their silhouette obscure.

        • Pedestrians who are carrying large baggage, holding an umbrella, etc., hiding part of their body.

        • Pedestrians who are bending forward or squatting.

        • Pedestrians who are pushing a stroller, wheelchair, bicycle or other vehicle.

        • Groups of pedestrians which are close together.

        • Pedestrians who are wearing white and look extremely bright.

        • Pedestrians in the dark, such as at night or while in a tunnel.

        • Pedestrians whose clothing appears to be nearly the same color or brightness as their surroundings.

        • Pedestrians near walls, fences, guardrails, or large objects.

        • Pedestrians who are on a metal object (manhole cover, steel plate, etc.) on the road.

        • Pedestrians who are walking fast.

        • Pedestrians who are changing speed abruptly.

        • Pedestrians running out from behind a vehicle or a large object.

        • Pedestrians who are extremely close to the side of the vehicle (outside rear view mirror, etc.).

        *: For countries/areas specified as Region B, the pedestrian detection function may not be available.

    8. If the PCS warning light flashes or illuminates and a warning message is displayed on the multi-information display


      1. The pre-collision system may be temporarily unavailable or there may be a malfunction in the system.


        • In the following situations, the warning light will turn off, the message will disappear and the system will become operational when normal operating conditions return:


          • When the radar sensor or camera sensor or the area around either sensor is hot, such as in the sun.

          • When the radar sensor or camera sensor or the area around either sensor is cold, such as in an extremely cold environment.

          • When a front sensor is dirty or covered with snow, etc..

          • When the part of the windshield in front of the camera sensor is fogged up or covered with condensation or ice.

          • If the camera sensor is obstructed, such as when the hood is open or a sticker is attached to the windshield near the camera sensor.

        • If the PCS warning light continues to flash or remains illuminated or the warning message does not disappear even though the vehicle has returned to normal, the system may be malfunctioning. Have the vehicle inspected by any authorized Lexus dealer or repairer, or another duly qualified and equipped professional immediately.

    9. If VSC is disabled


      1. If VSC is disabled, the pre-collision brake assist and pre-collision braking functions are also disabled.

      2. The PCS warning light will turn on and "VSC Turned Off Pre-Collision Brake System Unavailable" will be displayed on the multi-information display.

  4. SYSTEM CONTROL


    1. Pre-collision Brake Assist


      1. When the driver depresses the brake pedal after the pre-collision system has determined that there is the possibility of a collision, brake fluid pressure is increased. If the possibility of a collision is still high, brake fluid pressure is further increased.

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    2. Pre-collision Braking


      1. When the pre-collision system determines that a collision is imminent, the system performs pre-collision braking control.

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  5. DIAGNOSIS


    1. Initial Check


      1. The driving support ECU assembly performs an initial check on the system for approximately 3 seconds after the engine 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 5 digit Diagnostic Trouble Code (DTC) in memory.