Somewhere I believe I read this is because a power wire is grounded out when the park switch is activated (plunger pushed in) suggesting a mixup in the wiring, that maybe the Park feed 12 V and general feed 12 volt are mixed, but it doesn’t really seem possible to mix up the wiring since on the +2 since there is a Four wire input from the dash switch terminating in the plastic plug that only fits one way into the park connector clipped onto the side of the wiper motor, which then goes to the three wires to the spade terminals (red yellow and blue) that plug into the 14 W motor. So tough to figure, Gordon.