Keagan's first tractor ride

Neighbor John has been waiting for the day that Keagan would not longer be intimidated by the tractor and take Keagan for a ride.  This summer they gave it a try but as soon as Keagan sat on the tractor with John he was nervous and just wanted down...and the tractor was not even on!  When John came over last week with his tractor to help us with some horse chores Keagan looked intrigued.  So up he went and at first he was a little hesitant.  Then John stopped the tractor and Keagan got to play with some knobs and he fell in love.  Now when we go over to John's house the tractor is in the garage and Keagan likes to give it a good pat if we walk past it.  The only thing of concern is that the tractor usually has mud on the wheels and Keagan wants to get all that dirt off.  He has to take care of his tractor now that he has realized its potential :)

What does this button do?

Oh...it turns the light on in the back!