its a really cool feature that i have only used a few times. so in order for it to work you 1.need to be in 4lo. 2. be down in 1 on the shifter/gears. and C. push the button. when you use it the jeep automatically applies the brakes for you when doing a steep decent. it allows you to focus on your line a little bit more and not worry about braking. to turn it off just push the button again and the system will slowly unapply the brakes for you.
its really cool but weird at the same time cause you want to hit the brake! when i took my 101 class at rausch creek in pa the instructor told us to put our feet flat on the floor. it was the weirdest feeling ever!