My wipers have the same issue.
They always cycle once when I adjust the passenger mirror.
They will cycle once randomly (not always) when I use the climate control.
Has done this for years. I thought it might be the combination switch.

Wiper relay would be the easy fix.
Where is the wiper relay?



Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end