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As John wrote, the "self-parking" feature is inside the wiper moter and gearcase enclosure. It probably is a hard copper leaf spring switch arm that is moved by a cam on the slowest-speed rotating gear-- the one that moves the wiper arms via a crank and connecting rods. The cam has a high spot that makes the leaf spring open the circuit and disconnect the power to the motor. This high spot disconnect happens when the wiper blades are in their lowest position. Otherwise the cam keeps current flowing to the motor. Your dash wiper switch gives a parallel source of power that powers the motor in all wiper arm positions. And there's a wiring feature that makes the motor stop quick when the cam switch opens. That's why it takes so many wires to run a one-speed wiper motor.
This cam-actuated copper switch arm is flexed with every sweep of the wipers, which is a metal fatigue-causing situation. The arm can break off. This lets the wiper arms coast to stop in any position, so you have to time your shut-off at the dash switch. If the broken leaf falls across the wrong electrical contacts in there, it shorts the circuit and blows the fuse. All this happened to me in a 1961 VW in 1968, at the beginning of 75 rainy night miles going east from San Diego on the old, two-lane US 80. Later I had to take out the broken switch to restore any wiper function. Lived with timed shut-off thereafter. SWF-made motor, but typical.
But first check that all the wires to the motor are soundly connected in the correct positions.
Charles Greenlaw, Sacramento Calif.
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