Toyota USA shows you how to operate the headlights of the 2010 Prius. Follow this guide to operate the headlights on the 2010 Prius: To turn on the headlights, use the switch on the end of the left hand stalk. Rotate it once to turn on the parking lights, twice to turn on the headlights. The fog lights are switched on my rotating the inner control ring. If your model comes with LED headlamps, you can turn on the headlamp washers by pushing the button located to the left of the steering wheel.