Toyota Avalon Service & Repair Manual: System Description

SYSTEM DESCRIPTION

GENERAL

(a) 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 radio and display receiver assembly) and by sounding a buzzer.

FUNCTION OF COMPONENTS

Component

Function

Ultrasonic Sensor

Detects the distance between the vehicle and an obstacle

  • No. 1 Clearance Warning Buzzer
  • No. 2 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 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 ON/OFF signal to the clearance warning ECU assembly

Steering Pad Switch Assembly

Enables, disables or cuts off the operation of the intuitive parking assist 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 and display receiver assembly
  • 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 combination meter assembly via CAN communication

Main Body ECU (Multiplex Network Body ECU)

Transmits the destination information to the clearance warning ECU assembly

ECM

Transmits the shift position signal to the clearance warning ECU assembly

Radio and Display Receiver Assembly

- Multi-display

  • Receives the ultrasonic sensor information via CAN communication and sends it to the multi-display through the digital communication line
  • 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
  • Parking Assist ECU*1
  • Television Camera Assembly*2

Receives the ultrasonic sensor information via CAN communication and sends it to the multi-display through the video signal cable.

Headup Display (Meter Mirror Sub-assembly)*3

Receives the ultrasonic sensor information via CAN communication and sends it to the headup display

  • *1: w/ Panoramic View Monitor System
  • *2: w/ Parking Assist Monitor System
  • *3: w/ Headup Display System

OPERATION EXPLANATION

(a) 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

  • Engine switch is on (IG).
  • Intuitive parking assist system is on.
  • Shift lever in any position other than P.
  • Vehicle speed is less than approximately 10 km/h (6 mph).

Front Center

  • Engine switch is on (IG).
  • Intuitive parking assist 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

  • Engine switch is on (IG).
  • Intuitive parking assist 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 and display receiver assembly, the combination meter assembly and the No. 1 clearance warning buzzer and the No. 2 clearance warning buzzer. The approximate distance between the vehicle and the obstacle is then indicated, and the buzzer sounds.

HINT:

Refer to Detection Range Measurement and Display Inspection.

Click here

COMMUNICATION SIGNALS OF COMPONENTS

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".

(a) Initialization mode:

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

(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 assembly provides power to the first sensors in each series (front corner ultrasonic sensor RH and rear corner ultrasonic sensor RH).

(2) After the power is supplied, the front corner ultrasonic sensor RH and rear corner ultrasonic sensor RH 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 ultrasonic sensor RH and rear corner ultrasonic sensor RH 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 center ultrasonic sensor RH and rear center ultrasonic sensor RH) 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 corner ultrasonic sensor LH or rear corner ultrasonic sensor LH). Initialization ends when ID allocation to all ultrasonic sensors is completed.

(b) 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.

    Problem Symptoms Table

    System Diagram

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