For $25 a year you can get an alldatadiy.com account. They have diagnostic charts for the switch with correct voltages etc. But your problem is correctible and just a nuisance right now. Maybe let the condition go for now and see if it improves or gets worse.
They had something for wipers always on. With your condition I would wonder if the wipers have enough room to actually park. Did the wipers get caught on something and move a little bit in their sockets?
I don't have the service manuals so I couldn't check those.