TOYOTA PARKING ASSIST-SENSOR SYSTEM SYSTEM DESCRIPTION


  1. GENERAL


    1. This TOYOTA parking assist-sensor system uses the No. 1 ultrasonic sensors to detect any obstacles to the rear of the vehicle. The system then informs the driver of the distance between the sensors and the obstacles as well as their positions by sounding the No. 1 clearance warning buzzer.

  2. FUNCTION OF COMPONENTS

    Component Function
    No. 1 ultrasonic sensor Consists of a sensor portion that transmits and receives ultrasonic waves and a pre-amplifier that amplifies them. The No. 1 ultrasonic sensor outputs the ultrasonic transmission and reception signals to the clearance warning ECU.
    Clearance sonar main switch Turns the TOYOTA parking assist-sensor system on and off.
    No. 1 clearance warning buzzer Emits an intermittent sound to inform the driver that the clearance warning ECU has detected an obstacle within the predetermined ranges.
    Clearance warning ECU Judges the approximate distance between the vehicle and the obstacle based on the signals from the No. 1 ultrasonic sensors and sends the buzzer signal to the No. 1 clearance warning buzzer.
    Combination meter Receives the vehicle speed signal from vehicle speed sensor, and then sends the signal to the clearance warning ECU.
    Park / neutral position switch*1 Turns on when the shift lever is moved to P or R.
    Back-up light switch*2 Turns on when the shift lever is moved to R.

    *1: for Automatic Transmission

    *2: for Manual Transmission

  3. OPERATION EXPLANATION


    1. The No. 1 ultrasonic sensors operate under the conditions shown in the table below.

      Sensor Operating Condition
      No. 1 Ultrasonic Sensor

      • Ignition switch ON

      • Clearance sonar main switch is on

      • Shift lever moved to R

    2. When the system operates, the clearance warning ECU transmits ultrasonic waves from the No. 1 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. Based on this information, the clearance warning ECU sends signals to the No. 1 clearance warning buzzer. The distance between the obstacle and the vehicle is then indicated by the sounding of the buzzer.

      Tech Tips

      Refer to Operation Check for operation details Click here.

  4. COMMUNICATION SIGNALS OF COMPONENTS

    Tech Tips


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

    • The sensors are connected in a "daisy chain".


    1. Initialization mode:

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

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      1. When any of the following conditions are met, the clearance warning ECU provides power to the No. 1 ultrasonic sensor RH:


        • The ignition switch is turned ON.

        • The sensor operating conditions (described previously) are met and the clearance sonar main switch is turned on.

        • The vehicle speed is below 10 km/h (6.2 mph).

      2. After the power is supplied, the No. 1 ultrasonic sensor RH enters 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 this sensor.

      3. The No. 1 ultrasonic sensor RH receives the ID allocation signal from the ECU and performs self-diagnosis. When the sensor self-diagnosis is complete, the ECU sends an ID allocation confirmation signal to the sensor.

      4. After the ID allocation confirmation is performed, the ECU provides power to the No. 1 ultrasonic sensor LH via the No. 1 ultrasonic sensor RH. In the same manner as the No. 1 ultrasonic sensor RH, the No. 1 ultrasonic sensor LH enters standby mode. When a certain amount of time has elapsed, the ECU sends an ID allocation signal to the No. 1 ultrasonic sensor LH.

      5. Initialization ends when ID allocation to all ultrasonic sensors is complete.

    2. Detection mode:

      After initialization mode is complete, the system switches into detection mode. In detection mode, the clearance warning ECU sends information request signals and sensor activation signals to the No. 1 ultrasonic sensors and receives detection result signals from the sensors.


      1. The clearance warning ECU regularly sends ID signals, information request signals, and sensor activation signals to each No. 1 ultrasonic sensor according to the communication schedule.

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

      3. The No. 1 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.