Toyota Sienna Service Manual: Precaution

1. NOTES FOR CLEARANCE SONAR SYSTEM

1.  Under the following conditions, the sensor of the clearance sonar may not operate properly:

1.  Foreign matter such as snow or mud gets on the sensor (the detection function will return to normal when the foreign matter is no longer present).
2. The sensor is frozen (the detection function will return to normal if the temperature of the sensor rises).

HINT: Especially in cold weather, a malfunction warning may be indicated and the sensor may not be able to detect any obstacles due to a frozen sensor etc.

2.  The detection range of the clearance sonar may be affected by the following conditions:

1.  Foreign matter such as snow or mud gets on the sensor.
2.  In excessively hot or excessively cold weather.

3.  Under the following conditions, a parking sonar may produce erroneous detections:

1.  Something that generates ultrasonic waves approaches. Example of these things include the horn of another vehicle, the sound produced by the engine of a motorcycle, or the sound produced by the air brakes of a large-sized vehicle.
2.  The vehicle gets caught in a downpour, or something such as mud or water splashes on the vehicle's body.
3.  The vehicle is largely tilted at a large angle.
4.  Accessories that interfere with the system are mounted on the vehicle.
5.  Foreign matter such as snow or mud gets on the sensor.
6. Another vehicle with a similar clearance sonar system is nearby.
7.  The vehicle is equipped with a towing hook.

4.  The clearance sonar may not detect the following items:

1.  Thin objects such as wire or rope.
2.  Objects that absorb the ultrasonic wave such as cottons, snow, etc.
3.  Objects with a sharp edge.
4.  Short objects.
5.  Objects with a part that projects upward a large distance.

5. Other conditions:

1.  The sensor does not detect an object that is lying just under the bumper. The sensor may also stop or intermittently detect objects lower than the sensor, or thin fence posts or pickets even they were previously detected.
2.  The sensor may not be able to detect objects when the sensor gets too close to the objects.
3.  The sensor may not operate properly if it has been subjected to a strong impact. An example would be if the sensor has been stuck with great force by an object.