Problems with the wiper parking circuit or wiper motor can cause the windshield wipers not to stop in the proper position.Google+
Car Problem Reports
Dodge Caravan Wipers don't stop in proper position due to wiper parking circuit/motor problems
Dodge Caravan Problem
Sometimes wipers can't be shut off even when ignition is turned off. I just let them go and after 10 minutes or so they finally stop. Sometimes they stop in proper position ; other times at some other point on the windshield. I have noticed this is usually only a problem when it is not raining, like when using the wipers/washer to clean windshield. And sometimes the wipers will just come on by themselves.