When they don't work with the wiper switch in the "on" position locate the wiper motor and tap on it and see if the wipers then work (if so the motor is bad), wiggle the wires at the motor see if you have bad connections, wiggle the wires at the wiper switch see if they then work if so perhaps bad connections but it sounds like a bad switch, only a guess without being able to trace the wiring and do proper tests. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online