System Description [08/2015 - 08/2019]

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 obstacles as well as their positions by indicating them on the multi-information display in the combination meter and multi-display assembly and by sounding a buzzer.

FUNCTION OF COMPONENTS

Component	Function
Steering Pad Switch Assembly - Multi-Function Switch (Clearance Sonar Main Switch)	Operating this switch enables, disables or cuts off the operation of the intuitive parking assist system.
Driving Support Switch Control ECU	Receives an intuitive parking assist system on/off signal from the multi-function switch of the steering pad switch assembly and transmits it to the clearance warning ECU.
No. 1 Ultrasonic Sensor	Detects the distance between the vehicle and an obstacle.
No. 1 Clearance Warning Buzzer	Sounds when the intuitive parking assist-sensor system is turned on approximately 2 seconds or more after the engine switch is turned on (IG) (does not sound when the intuitive parking assist-sensor system is turned on within 2 seconds of the engine switch being turned on [IG])*. Sounds to inform the driver of the distance to an obstacle.
Combination Meter Assembly - Multi-information Display	Displays the location of an obstacle and the approximate distance between the vehicle and obstacle. Informs the driver of ultrasonic sensor malfunctions.
Combination Meter Assembly - Clearance Sonar Indicator	Illuminates to inform the driver while the intuitive parking assist system power is on (the engine switch is on [IG] and the intuitive parking assist system is on).
Combination Meter Assembly	Transmits the vehicle speed signal to the clearance warning ECU.
Clearance Warning ECU	Judges the approximate distance between the vehicle and an obstacle based on the signals from the ultrasonic sensors and sends this value to the multi-information display in the combination meter assembly and multi-display assembly. Sounds the buzzer.
Main Body ECU (Multiplex Network Body ECU)	Transmits the destination information to the clearance warning ECU.
Multi-display Assembly	Receives the display signals from the clearance warning ECU and displays them on the display panel.
Multi-media Module Receiver Assembly	Receives the display signals from the clearance warning ECU and displays them on the display panel. Transmits the customization information displayed on the multi-display to the clearance warning ECU.

HINT:

*: The buzzer does not sound when the engine switch is on (IG) while the clearance sonar main switch is on.

OPERATION EXPLANATION

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 Sensor	Engine switch is on (IG). Intuitive parking assist system is on. Shift lever is in any position except P. Vehicle speed is less than approximately 10 km/h (6.2 mph). The sensors stop operating when the vehicle speed exceeds approximately 15 km/h (9.3 mph), and start operating when the vehicle speed drops below approximately 10 km/h (6.2 mph).
Front Center Sensor	Engine switch is on (IG). Intuitive parking assist system is on. Shift lever is in any position except P and R. Vehicle speed is less than approximately 10 km/h (6.2 mph). The sensors stop operating when the vehicle speed exceeds approximately 15 km/h (9.3 mph), and start operating when the vehicle speed drops below approximately 10 km/h (6.2 mph).
Rear Corner Sensor	Engine switch is on (IG). Intuitive parking assist system is on. Shift lever is in R.
Rear Center Sensor	Engine switch is on (IG). Intuitive parking assist system is on. Shift lever is in R.

When the system operates, the clearance warning ECU 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.

Based on this information, the clearance warning ECU sends signals to the indicator and clearance warning buzzer. The appropriate distance between the vehicle and the obstacle is then indicated, and the buzzer sounds.

HINT:

Refer to Detection Range Measurement and Display Inspection (Refer to OPERATION CHECK [08/2015 - 08/2019] ).

COMMUNICATION SIGNALS OF COMPONENTS
HINT:
- Allocation refers to the process of the clearance warning ECU 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.
  
  Fig 1: Initialization Mode
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  1. When the initial check is operating (the engine switch is on [IG] and the intuitive parking assist system is on), the clearance warning ECU provides power to the first sensors in each series (front corner sensor LH and rear corner sensor LH).
    HINT:
    
    Refer to Self-check Function Inspection (Initial Check) (Refer to OPERATION CHECK [08/2015 - 08/2019] ).
  2. After the power is supplied, the front corner sensor LH and rear corner sensor LH 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 corner sensor LH and rear corner sensor LH receive the ID allocation signal from the ECU and perform self-diagnosis. When the sensor self-diagnosis is completed, the ECU sends an ID allocation confirmation signal to these sensors.
  4. After the ID allocation confirmation is performed, the ECU provides power to the second sensors in each series (front center sensor LH and rear center sensor LH) 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, which is in the front series (front corner sensor RH) and rear series (rear corner sensor RH). Initialization ends when ID allocation to all ultrasonic sensors is completed.
2. Detection mode:
  After initialization mode is completed, the system switches into detection mode. In detection mode, the clearance warning ECU 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.