A turn signal switch is that part of a turn signal system by which the operator of a vehicle causes the turn signal lamps to function. A Class A turn signal switch may be used on any vehicle but is intended for use on multipurpose passenger vehicles, trucks, and buses that are 80 in or more wide overall. A Class B turn signal switch is intended for use in passenger cars, motorcycles, and multipurpose passenger vehicles, trucks, and buses of less than 80 in overall width.