LEXUS PARKING ASSIST-SENSOR SYSTEM(w/o Intelligent Clearance Sonar System) SYSTEM DESCRIPTION


  1. GENERAL


    1. This system uses ultrasonic sensors to detect any obstacles at the corners and the rear of the vehicle. The system then informs the driver of the distance between the sensors and an obstacle as well as their positions by indicating them on the multi-information display (on the combination meter assembly), multi-display (on the multi-display assembly) and by sounding a buzzer.

  2. FUNCTION OF COMPONENTS

    Component Function

    • Front Corner Ultrasonic Sensor (FL sensor)

    • Front Corner Ultrasonic Sensor (FR sensor)

    • Front Center Ultrasonic Sensor (FLC sensor)

    • Front Center Ultrasonic Sensor (FRC sensor)

    • Rear Corner Ultrasonic Sensor (RL sensor)

    • Rear Corner Ultrasonic Sensor (RR sensor)

    • Rear Center Ultrasonic Sensor (RLC sensor)

    • Rear Center Ultrasonic Sensor (RRC sensor)

    		 Detects the distance between the vehicle and an obstacle
    No. 1 Clearance Warning Buzzer Sounds to inform the driver according to the distance to an obstacle
    Multi-information Display (on Combination Meter Assembly)

    • Displays the location of an obstacle and the approximate distance between the vehicle and the obstacle

    • Displays a malfunction of the ultrasonic sensor to inform the driver
    Clearance Sonar Indicator (on Combination Meter Assembly) Illuminates to inform the driver while the LEXUS parking assist-sensor system power is on (the power switch is on (IG) and the LEXUS parking assist-sensor system is on)
    Combination Meter Assembly Transmits the ON/OFF signal to the clearance warning ECU assembly

    Steering Pad Switch Assembly

    - Multi-information Switch

    		 Enables, disables or cuts off the operation of the LEXUS parking assist-sensor system by transmitting the switch operation signal to the combination meter assembly
    Clearance Warning ECU Assembly

    • Judges the approximate distance between the vehicle and an obstacle based on the signals from the ultrasonic sensors and sends it to the multi-information display and radio receiver assembly

    • Judges the approximate distance between the vehicle and an obstacle based on the signals from the ultrasonic sensors, and sends it to the multi-information display, radio receiver assembly and parking assist ECU*1

    • Judges the approximate distance between the vehicle and an obstacle based on the signals from the ultrasonic sensors, and sends it to the multi-information display, radio receiver assembly and rear television camera assembly*2

    • Judges the approximate distance between the vehicle and an obstacle based on the signals from the ultrasonic sensors and sounds the buzzer

    • Receives the temporary mute setting signal and clearance sonar setting screen information from the radio receiver assembly via CAN communication
    Main Body ECU (Multiplex Network Body ECU) Transmits the destination information to the clearance warning ECU assembly
    Hybrid Vehicle Control ECU Transmits the shift position signal to the clearance warning ECU assembly
    Radio Receiver Assembly

    • Receives the ultrasonic sensor information via CAN communication line and sends it to the multi-display assembly through the digital communication cable

    • Transmits the customize information on the multi-display assembly to the clearance warning ECU assembly

    • Sends the temporary mute setting signal and clearance sonar setting screen information to the clearance warning ECU assembly via CAN communication
    Multi-display Assembly

    • Receives the video signals from the radio receiver assembly, and displays them on the display panel

    • Receives the video signals from the parking assist ECU, and displays them on the display panel*1

    • Receives the video signals from the rear television camera assembly, and displays them on the display panel*2
    Parking Assist ECU*1 Receives the ultrasonic sensor information via CAN communication and sends it to the multi-display assembly through the video signal cable
    Rear Television Camera Assembly*2 Receives the ultrasonic sensor information via CAN communication and sends it to the multi-display assembly through the video signal cable

    • *1: w/ Panoramic View Monitor System

    • *2: w/ Parking Assist Monitor System

  3. OPERATION EXPLANATION


    1. The operating conditions of each ultrasonic sensor differ according to the installation position as shown in the table below.

      Installation Position Operating Condition
      Front Corner

      • Power switch is on (IG).

      • LEXUS parking assist-sensor system is on.

      • Shift lever in any position other than P.

      • Vehicle speed is less than approximately 10 km/h (6 mph).
      Front Center

      • Power switch is on (IG).

      • LEXUS parking assist-sensor system is on.

      • Shift lever in any position other than P or R.

      • Vehicle speed is less than approximately 10 km/h (6 mph).
      Rear Corner

      • Power switch is on (IG).

      • LEXUS parking assist-sensor system is on.

      • Shift lever is in R.

      • Vehicle speed is less than approximately 10 km/h (6 mph).
      Rear Center

      When the system operates, the clearance warning ECU assembly transmits ultrasonic waves from the ultrasonic sensors. If these waves encounter an obstacle within one or more of the sensors ranges, the waves are reflected back to the sensors, which transmit them to the clearance warning ECU assembly.

      Based on this information, the clearance warning ECU assembly sends signals to the radio receiver assembly, the combination meter assembly and the No. 1 clearance warning buzzer. The approximate distance between the vehicle and the obstacle is then indicated, and the buzzer sounds.

      Tech Tips

      Refer to Detection Range Measurement and Display Inspection.

      Click here

  4. COMMUNICATION SIGNALS OF COMPONENTS

    Tech Tips


    • Allocation refers to the process of the clearance warning ECU assembly setting aside IDs for the sensors.

    • The vehicle has the sensors arranged in 2 groups. There is a front series and a rear series. The sensors are connected in a "daisy chain".


    1. Initialization mode:

      An ID is allocated to each sensor and sensor diagnosis is performed.

      B002HTSC01
      *1 Clearance Warning ECU Assembly *2 FRONT CORNER ULTRASONIC SENSOR (FR SENSOR)
      *3 FRONT CENTER ULTRASONIC SENSOR (FRC SENSOR) *4 FRONT CENTER ULTRASONIC SENSOR (FLC SENSOR)
      *5 FRONT CORNER ULTRASONIC SENSOR (FL SENSOR) *6 REAR CORNER ULTRASONIC SENSOR (RL SENSOR)
      *7 REAR CENTER ULTRASONIC SENSOR (RLC SENSOR) *8 REAR CENTER ULTRASONIC SENSOR (RRC SENSOR)
      *9 REAR CORNER ULTRASONIC SENSOR (RR SENSOR) - -
      *a Front - -

      1. When the initial check is operating (the power switch is on (IG) and the LEXUS parking assist-sensor system is on), the clearance warning ECU assembly provides power to the first sensors in each series (front left sensor and rear right sensor).

      2. After the power is supplied, the front left sensor and rear right sensor enter standby mode to receive an ID from the ECU. When a certain amount of time has elapsed, the ECU sends an ID allocation signal to these sensors.

      3. The front left sensor and rear right sensors receive the ID allocation signal from the ECU and perform self-diagnosis. When the sensor self-diagnosis is complete, the ECU sends an ID allocation confirmation signal to the sensors.

      4. After the ID allocation confirmation is performed, the ECU provides power to the second sensors in each series (front left center sensor and rear right center sensor) via the first sensors. In the same manner as the first sensors, the second sensors enter standby mode. When a certain amount of time has elapsed, the ECU sends an ID allocation signal to the second sensors.

      5. The above operation will be repeated until an ID is allocated to the last sensor (front right sensor or rear left sensor). Initialization ends when ID allocation to all ultrasonic sensors is completed.

    2. Detection mode:

      After initialization mode is completed, the system switches to detection mode. In detection mode, the clearance warning ECU assembly sends information request signals and sensor activation signals to the ultrasonic sensors and receives detection result signals from the sensors.


      1. The ECU regularly sends ID signals, information request signals, and sensor activation signals to each ultrasonic sensor according to the communication schedule.

      2. When a certain amount of time has elapsed (sensor detection operation is completed), the ECU sends an ID signal to the sensor to receive a detection result signal.

      3. The ultrasonic sensor sends a detection result signal or detection information signal to the ECU.

      4. The above operation is performed repeatedly for each ultrasonic sensor.