Bart's description of the wiper motor operation sounds more like the 1960s (and maybe earlier and later) version of a GM 2 speed wiper system. Definitely not like the one in my 57 GMC (and that I linked to above).
He is correct when describing the switching operation where the switch just provides a ground for either the high speed or low speed motor circuit. Every time the wiper system gets back to "park" it opens a switch that provides ground for the motor. If the switch is in the "high" or "low" position, a ground is provided and the motor continues to run through another cycle. If the switch is in the "off" position (ie. neither "high" nor "low" providing a ground) the motor stops.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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