Yep, you have a bad park switch.
When you turn the wipers off, you kill power to the motor..Duh...<G>.
Problem is, you never turn them off just as they hit the "park" position against the bottom of the windshield.
So, when you turn off the switch, you turn on power to a secondary circuit that keeps power to the motor through a "park switch" mounted on the motor.
This switch is closed all the time except when the wipers are all the way down. Then a cam opens the switch and stops them at that point.
Either you have a short in the wiring that is shorting the park wire to the regular run wire, or the switch on the motor or the cam that opens it has a problem.
Best bet, is to pull that cover off the motor gearbox and see what is what.
J.
