Wipers coming on at engine start

[JDMsurprise]

My 1997 Boxster (ROW) 5 speed has a bit of an odd startup condition. Occasionally, perhaps increasingly, the wipers will swipe once upon starting the engine. The switch position is off and that is all that occurs. The car has low kilometers, and doesn't appear to have had much in the way of hacking on the wiring harnesses. All ideas as to where I should troubleshoot first would be appreciated.
Thanks,
Cameron

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