98 SL wiper motor
 

My wipers only stop when they want to. They may rum for 30 seconds or several minutes before they stop in the park position Here's what happened, last week the blades froze to the windshield and when I turned them on the motor actually ripped the arm off of the splined shaft. I replaced the arm and now I have a shut off problem. It's not the switch on the steering column.

Has anyone ever took a motor apart to see how it works. I think this could be repaired if I could look inside. Seems like a trip mechanism is broken or misaligned.
I hate to just trash the motor unless it's totally unrepairable.

The electronic module, which would be the "logic" is what is causing this. It's part of the wiper motor and you need to replace the motor/module assembly. There is just a printed circuit board inside there, nothing fixable.

Hope this helps,
Brian