If I am reading the EVTM correctly, the fan and the wiper control module share circuit 57 to ground splicing in both at splice s100 but with the wiper control module grounding at g204 and the fan grounding at ground g103. g103 is is located at the right front of the engine compartment. g204 is behind the dash in the center.
This is the only thing that I see that they share. This really does not sound like a ground problem though. have you tried to disconnect the battery for about a half hour and then try again?
I wish I had the shop manual to go along with the EVTM. It would probably help alot.