The CTIS computer control panel runs the two CTIS systems (front and rear) and all five lockers. So you select your terrain on one side, your cargo weight on the other, and the computer adjusts the front and rear tire pressure and locks/unlocks the lockers appropriately.
In addition, there is a rocker switch on the dash that overrides the CTIS computer's selection on the lockers, to momentarily lock all of them. So if for example you are driving off road with the correct selections, but you suddenly encounter something unusual that causes you to get stuck, you can use that switch to lock all the lockers instantly to get unstuck.