This problem really upset me! The wipers wouldn't shut off until we could shut off the ignition. I then pulled the fuse. When we got it to the dealer, he found a problem with the control module that is integral to the motor assembly, so the entire thing had to be replaced at considerable cost. I seriously considered going to a used part, but decided against it because we expected to keep the car for quite a while.
Update from Feb 15, 2013: The car now has >176,000-miles on it and we haven't had this problem recur, so far. Hope to make it to 200,000 before replacing it. Our car stands outside all the time, so I guess moisture could be a problem. Hope the replacement resolves your problem. At this stage, if it happens again, it'll be replaced with a used unit.
We've also replaced all the window lifts once, and two of them twice.
A D V E R T I S E M E N T S
I should buy stock in wiper blades. I look stupid when the rain stops and i'm the only one with wipers still on.
- Sandra B., Conyers, GA, Western Sahara