There is a troubleshooting manual for the SmartWheel in the Members' Coach Assist section.
The SmartWheel model you have has an LED diagnostic light on the control module.
You can have someone activate the wipers and see if the LED light indicates the signal is reaching the Controller (the LED flashes appropriately). If the signal from the steering wheel wiper button is getting to the Controller, then you may have a faulty wiper motor, or wiring issue to the Wiper motor. The manual states the biggest source of problems is due to bad grounds.
If the signal is not getting to the Controller (the LED does not flash) then the Wiper button is bad, or the steering wheel clock spring is bad, or the wiring between the steering wheel and Controller is bad.
My SmartWheel is an older model, but I had a problem with the Cruise Control. it turned out to be a bad wire crimp in the connector that plugs into the Controller. So an easy test for this, is to give each wire a gentle tug. If one pulls out of the connector then you found your problem. Also, its not a bad idea to unplug the connectors and spray some electrical contact cleaner on them.