Similar to all other auto parts, an alternator needs to be fastened properly with meticulous attention. In this case, the battery terminal of the car must be disconnected first in order to avoid any electrical related issues. The old unit is removed by untangling the battery cables, unbolting the screws, and taking off the drive belt. An new alternator these days comes with it preinstalled to the engine and bolted down to the brackets of the engine. There is also some reasonable static tension on the drive belt which ensures that the engine drives the alternator and not the other way around. The rest of the wires and the battery is connected, and the last thing to do is to turn on the vehicle to make sure that whatever is within the car and all components connected to the alternator functions.