I have a question regarding the rain sense wipers. For me I have it selected to "ON" and when I switch on my wipers it seems they only wipe when there's enough moisture on the glass. Is that correct operation? I am aware the headlights come on automatically when there's so many swipes of the wipers too. Maybe I'm misunderstanding how they work? The less moisture, the less they move, the more the moisture the more they move correct? Regardless of where i set my wiper switch?