I believe (at least on my 2001 this is true) the grounds for the wiper motors are a small black wire on a small a screw into the fire wall, up close to the motor. Check to make sure that ground isn't corroded or the screw so rusty it isn't making good contact.
It seems like everything else in the engine bay is grounded back to the PDC, except for those things.

 

Aim4squirrels was right on it! Thanks a heap; the ground wire connectionwas bad. Now I have wipers again, and just in time for a full week of beautiful sunny weather. There are 2 ways I know for sure to make it rain: -lose your wipers, and -hang the laundry out on the line. Great help!

 

Mine stick and don't return to the down position if I switch them off during a cycle. My Caprices have all done this as well. On them it was a bad logic board on the motor. My guess is it's the same on the Dodge.