Pull the plugs at the wiper motor then squeeze and remove the plastic cover. Reconnect the wiring. Now engage the wipers. You will see a white roller wheel spinning under a metal rectangle. Use WD 40 on that wheel while gently lifting the metal piece. They should swipe a couple more times, then come to rest. The wiper motor gets gummed up with engine oil fumes over the years and will cause the roller wheel to stick. Doubt if the switch is faulty. In rare cases the circuit board in the wiper motor develops an open solder joint and needs replaced. I used to fix this issue in the service drive when I was a service advisor with Cadillac, Buick. Spraying fixed 95% of them.