Toyota 2014 Sienna Manual page 289

Rain-sensing windshield wipers (if equipped)
When "AUTO" is selected, the wipers will operate automatically
when the sensor detects falling rain. The system automatically
adjusts wiper timing in accordance with rain volume.
When "AUTO" is selected, the sensor sensitivity can be adjusted
as follows by turning the switch ring:
Type A
SIENNA_OM_OM45483U_(U)
2-3. Operating the lights and wipers
Off
Rain-sensing wiper
operation ("AUTO")
Low speed
operation
High speed wiper
operation
Temporary operation
2
wiper
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