The windshield wiper switch is located inside your car and is attached to the steering column. When the driver flips the wiper control, the wiper motor turns on/off the wipers. If the wiper blades are not stopping, it may be the motor itself and not the switch or it may be the "park" switch. Your mechanic should verify the problem before replacing the switch. Windshield wiper systems are not usually a part of routine maintenance and servicing. Windshield wiper switches will usually last a very long time, so they don't need much preventative action.