It's only function is to keep you from having to feather the clutch on steep terrain after starting the truck. If you kill the truck on a very steep incline, and are in a position that rolling backwards will cause you big problems, all you have to do is press the cancell button and start the truck with the clutch ingaged and in gear. The truck will travel forward and start at the same time, preventing you from rolling backwards and having to feather the clutch to get moving forwards again. It can be rough on starters and flywheels, unless it's used while the truck is in low range. I have only needed it one time; it kept me from rolling off a very steep bluff.