use it when you are driving in snowy conditions
you can get the .pdf of the manual. read here.I'm glad there is a forum for Catera owners as I am clueless. I bought a used Catera and did not get the book with it - I couldn't find anywhere online I could buy a book (cheap anyway) so I have a question - there is a button that looks like a snowflake in several spots in my Catera - what does it do?