the adjustment **** is for the sensitivity of the sensor... the sensor is light based, bounces light off the glass and sees how much comes back, if the glass is clean and dry, itll all come back, like the inside of a prism. if its dirty or wet then it knows it, and the wipers will wipe. adjusting them doesnt slow down the wiper speed, or add a delay, just changes the threshold of returned light as to when to wipe and not. it should work, if not, take it in

 

i was going for a drive yeasterday on a nuce sunny day turned on my rear wiper and played with the dial I noticed a significant difference in the time delay with the **** adj for my rear wiper.