Help!!! GM, you will probably be able to explain this to me the best. The Cayenne has the reduction gear which is engaged with one flick of the center rocker. Two flicks gives me the message that the longitudinal lock is engaged, I thought this locked front and rear diffs for 4 wheel drive. I've been warned against driving on dry pavement with this engaged as it is said to be detrimental to the dive components. In short what does the longitudinal lock mean?