I am sorry. I am new to the Jeep brand and 4x4 vehicles. I tried to look it up on Jeep.com and the owner's manual with no results. So please educate me on this selec-terrain system. What are the ACTUAL differences between auto, mud, sand, and snow (not just what they are for)? Is the rear axle always engaged or is it on-demand 4x4. Or it this system just a fancy name for traction control via braking and power reduction? I tried to test it out on a dirt road couple days ago, the system gave the vehicle sudden surge of traction, felt like as if the rear axle kicked in when I spun my tires and speed through a turn.
Jeep has a video on their site that has all the info that you are looking for http://www.jeep.com/en/4x4/index.html#ActiveDrive1*
The actual differences are just in the amount of traction control the computer applies. It essentially uses the brakes to prevent too much slipping on different terrain.