In her Explorer, the box is on the driver's side mounted to the fender. You lift the lid and the relays are inside. I'll try to remember to take alook at the schematics I have at home. Your's is too old to be able to down load the manual from the Ford web site since they stopped (or started) at 1996 but the 1996 manual might give you a place to start. Try this link:
https://www.flmowner.com/servlet/Con...OwnerGuidePage
or this one:
http://www.motorcraftservice.com/pub.../96ranog1e.pdf
Page 313 shows the power distribution box. You are looking at the wiper hi-lo relay and the wiper run relay.
If swapping them out doesn't fix the problem, than you might be looking at replacing your multi-function switch which is the whole switch assembly that has the turn signals, hazard light switch, and wiper switch.