I checked my Dodge pickup manual so you could at least know where they
are there. If it's like an 81-84 if you can track from the switch. In
mine, headlight and w/s wiper switch title lamp (which is combined) 18
guage orange wire on that diagram, you may be able to follow it down. On
my diagram, it goes to a little circle -- usually a fusible link BUT,
looks a little confusing because there are the orange wire mentioned
that goes through, plus two other orange wires! totaling six in and out.
YUK! The one mentioned goes to the ash reciever lamp provision and just
below on the diagram is the glove box lamp provision (try the glove box)
 It then disapperars and other wires go out. I asked a friend who
thinks it is a fusible link. Book says headlight is a fusible link (as a
"for instance" but does not mention wiper. From w/s wiper provision (for
speeds), all wires doing there are 18 guage and it mentions the switch
going there as 18 guege brown and yellow which goes to the w/s wiper
motor. try looking along there as it doesn't mention a fusible link.

On the 85-88 it id clearer. It indicates an 18 guage dark blue wire
going to the wipers, coming from a fuse set of three including ignition
switch and radio.

Best of luck and let me know if this doesn't help. I'll do what I can
rachel