Toyota Sienna Service Manual: System description
1. GENERAL
- 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 the obstacles as well as their positions by indicating them on the clearance sonar display and by sounding a buzzer.
2. FUNCTIONS OF COMPONENTS
|
Components |
Function |
| Ultrasonic Sensor | Ultrasonic sensor consists of a sensor portion that transmits and receives ultrasonic waves and a pre-amplifier that amplifies the waves. The ultrasonic sensor outputs the ultrasonic transmission and reception signals to the clearance warning ECU. |
| Clearance Sonar Main Switch | Turns the clearance sonar system on and off. |
| Clearance Warning Buzzer | Emits an intermittent sound to inform the driver that the ECU has detected an obstacle within prescribed ranges. |
| Clearance Warning ECU | Judges the approximate distance between the vehicle and the obstacle based on the signals from the ultrasonic sensors and sends the display signal to the clearance sonar indicator and the buzzer signal to the clearance warning buzzer. |
| Indicators | Displays the location of the obstacle and the approximate distance between the vehicle and the obstacle. |
| Speed Sensor | Detects speed of each wheel and inputs the data into the clearance warning ECU via the combination meter. |
| Park / Neutral Position Switch (A/T) | Sends a signal that activates the clearance sonar system when the shift lever is moved to the R position. |
3. OPERATION EXPLANATION
- The clearance warning ECU determines whether the clearance sonar system should be operated based on the clearance sonar main switch on/off stratus, the shift position and the vehicle speed.
- 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 the clearance warning buzzer. The approximate distance between the vehicle and the obstacle is then indicated, and the buzzer sounds.
HINT: Refer to "OPERATION CHECK" for detailed operation
Parts location
SYSTEM DIAGRAM
...
How to proceed with
troubleshooting
1 VEHICLE BROUGHT TO WORKSHOP
2 CUSTOMER PROBLEM ANALYSIS
3 CHECK INITIAL CHECK FUNCTION
4 PROBLEM SYMPTOMS TABLE
THE CORRESPONDING SYSTEM DOES NOT EXIST (Go to step 5)
5 BASED ON THE MALFUNCTION ...
Other materials:
No. 2 Clearance Warning Buzzer Circuit
DESCRIPTION
The clearance warning ECU receives the ultrasonic sensor signal to sound the
rear warning buzzer.
WIRING DIAGRAM
INSPECTION PROCEDURE
1 CHECK HARNESS AND CONNECTOR (CLEARANCE WARNING ECU - AIR CONDITIONER
AMPLIFIER)
Disconnect the connectors from the clearance warning ...
Data list
HINT:
Reading the DATA LIST displayed on an intelligent tester
enables values, including those of the switches, sensors,
and actuators, to be checked without removing any
parts. Reading the DATA LIST as the first step in
troubleshooting is one method to shorten diagnostic
time.
NOTICE: ...
ECM Communication Stop Mode
DESCRIPTION
Detection Item
Symptom
Trouble Area
ECM Communication Stop
Mode
"Engine" is not displayed on the "Communication
Bus Check" screen of the intelligent tester
Applies to "ECM Communication Stop Mode" in ...
