OldSub,
I don't know if the wiper motor was designed for one speed--it has 2 terminals. I put in the wiper switch which has 3 terminals (for 2 speeds I believe) but only one wire attached now - goes to the motor.
I got an electric washer motor to use separately. It has two wires--one goes to a hot wire, the other some kind of ground I guess. Can I turn the existing wiper motor into a 2 speed or would I have to put in a different motor?