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:
Reassembly
1. INSTALL FRONT DISC
(a) Aligning the matchmarks, install the front disc.
HINT:
Select the installation position where the disc has
the minimum runout.
2. INSPECT DISC RUNOUT
(a) Temporarily fasten the disc with the hub nuts.
Torque: 103 N*m (1,050 kgf*cm, 76 ft.*lbf)
(b) Using a ...
Air conditioning unit
COMPONENTS
...
Vehicle Speed Signal Circuit between Multi-display and Combination
Meter
DESCRIPTION
This circuit is necessary for the ASL (Auto Sound Leveliser) built into the
radio receiver.
Speed signals are received from the combination meter and used for the ASL.
The ASL function automatically adjusts the sound data in order to enable hearing
the clear audio sound
even ...