An activation circuit provides the controller the signal it needs to run the golf cart. Without these signals, the controller does not receive the input it needs, and on this smart of a golf cart, it will shut the whole system down. Unlike the older series systems, the controller really does handle everything; it just requires input from you via the different switches to know what to do. The E-Z-GO DCS and PDS Electric Micro-Switch, for example, is in the floorboard of the cart, tucked away in a little black box with the throttle sensor.If this golf cart switch is not activated, allowing its signal to pass to the controller, nothing will happen. Even if the throttle sensor sends everything it's supposed to, you are out of luck without a working switch. There are several others on the caddie, like the key switch and the forward and reverse. If you are having issues, call a tech at Buggies Unlimited, they will be happy to help you find what's causing the problem.