System Description

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 (in the combination meter assembly) and multi-display (w/ Navigation System) and by sounding a buzzer.

• *1: The buzzer does not sound when the power switch is on (IG) while the clearance main switch is on.
• *2: w/o Navigation System
• *3: w/ Navigation System (for DVD)
• *4: w/ Navigation System (for HDD)

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 Sensor	Power switch is on (READY). Intuitive parking assist system is on. A shift state other than park (P) has been selected. Vehicle speed is less than approximately 10 km/h (6.2 mph). The sensors stop operating when the vehicle speed exceeds 15 km/h (9.3 mph), and start operating when the vehicle speed drops below 10 km/h (6.2 mph).
   Rear Corner Sensor	Power switch is on (READY). Intuitive parking assist system is on. Reverse (R) has been selected.
   Rear Center Sensor	Power switch is on (READY). Intuitive parking assist system is on. Reverse (R) has been selected.

   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 indicator and the 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 .

HINT: 

• 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.

   Fig 1: Identifying Communication Signals Of Components (Initialization Mode)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. When the initial check is operating (the power switch is on (IG) and the intuitive parking assist system is on), the clearance warning ECU assembly provides power to the first sensors in each series (front left sensor and rear right sensor).

      HINT: 

      Refer to Self-check Function Inspection (Initial Check). Refer to OPERATION CHECK .

   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 sensor 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 right 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, which is in the rear series (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 into 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.