Toyota 2014 Sienna Manual page 351

The Rear Cross Traffic Alert function
The Rear Cross Traffic Alert Functions when your vehicle is in
reverse. It can detect other vehicles approaching from the right or left
rear of the vehicle. It uses radar sensors to alert the driver of the
other vehicle's existence through flashing the outside rear view mirror
indicators and sounding a buzzer.
Approaching vehicles
Detection areas
SIENNA_OM_OM45483U_(U)
2-4. Using other driving systems
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