Hey, well I just cleaned up my combination switch and the double sweep of the wipers when I start the car is gone. I’m not sure how that all happens but perhaps there is some arcing that trips the circuitry in the wiper relay. There are some solid state parts in there that handle triggering two sweeps for the wiper washer action when the washer pump is activated. Maybe just maybe that circuit is easily triggered by noise on the wiper switch that happens as it gets energized by the ignition.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles