Toyota SIENNA 2011 Quick Reference Manual page 23

Distance control mode
The distance control mode will cruise at a set speed, decelerate to
maintain a selected distance from a slower vehicle traveling in front of
you, and accelerate back up to the selected speed if the vehicle in front
changes lanes or speeds up.
To set, cancel and resume a speed Refer to "Functions" in the Cruise
Control section, and your Owner's Manual for more details.
NOTE: Once vehicle speed is set, pushing lever up toward "+ RES" will
increase speed to the nearest 5 mph, and then in 5 mph increments.
Pushing lever down toward "- SET" will reduce speed in the same way.
LONG
MIDDLE
SHORT
To change the vehicle-to-vehicle distance
Push the distance button to cycle through the settings, which will change
progressively from LONG to MIDDLE to SHORT.
I n f o r ma t i o n P r o v i d e d b y :
21
Push
System ON/OFF
Push