Hobbies and Crafts How do you open the rear vent on a Toyota Sienna? How do you open the rear vent on a Toyota Sienna? Open the latch by pressing the circular black button, beneath the rear hatch glass, just to the right of the Toyota emblem. The window unlocks and pops open. Then lift the latch up and open the window. Related Posts:Why does a house need a plumbing vent?The 7 Best Popsicles in the world are available on Walmart.com.What is the most reliable year for Toyota Sienna?How many gallons of oil does a Toyota Sienna take?