Testing results are somewhat inconclusive. Grounding one of the non powered wires gives a healthy spark, but no wiper movement. Grounding the other non powered wire gives a weak spark and no movement. Turning the wipers to "high" and grounding the healthy spark wire starts the wipers and they will remain running after the ground is removed. Grounding the other wire reduced speed.
Bill I don't fully understand this description. Line by line:
"Grounding one of the non powered wires gives a healthy spark, but no wiper movement". I assume you are grounding the short wire directly from the wiper, disconnected from the line going to the wiper and no wires are connected to the switch. Seems to me that this would be the Red/Grn wire, but not sure. If it is, it should cause to wiper to run. But maybe not a good enough (clean) ground
"Grounding the other non powered wire gives a weak spark and no movement" Seems that is the Brn Grn wire. This is what I would expect, if you are grounding ONLY that one wire.
"Turning the wipers to "high" and grounding the healthy spark wire starts the wipers and they will remain running after the ground is removed". I don't understand why turning the switch to High has any effect unless you still have wires connected to the switch. Do you mean the previous steps were done with the wires attached?
"Grounding the other wire reduced speed.[/QUOTE]. SO YOU DO SEE two speeds !!!.
Bill I don't understand your conclusion. If you cannot duplicate the switch action by grounding the wires, which is all the switch does, then there is a problem in the wiring that you are not understanding.
Try grounding BOTH wires initially, that should run it slow. And while keeping the "big spark" wire grounded, and the wiper running, disconnect the other wire and see if the wiper speeds up.