Could be a few different thing's . The motor , relay , BCM - body control module , the switch etc.... Looking at a wiring diagram (do you know what a wiring diagram is ? ) I see fuse #15 10amp powers the wiper switch , the switch is an input to the BCM , The same fuse supply's B+ voltage to the control side of wiper hi/lo relay & the intermittent wiper relay . The BCM will energize these relay's after it receives a input from the wiper switch . Do you know how to test automotive electrical circuits using a wiring diagram an a DVOM - digital volt ohm meter ? Free wiring diagrams here
http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine . Under system click on body & accessories ,then under subsystem click on wiper/washer . Click the search button ,then the blue link . Having the BCM check for DTC'S - diagnostic trouble codes would be a good first step , could point to the problem .
Electric Testing Techniques You Need to Know
This is how to diagnose electrical problems .