: Why do windshield wipers trigger a cycle when switched off?


It seems that even when wipers are turned off, they always cycle one more time at the moment of switching them off. The make or model of the car does not seem to matter.

In: 2

To make sure they end up at their correct resting place, without that extra cycle, they would stay right where they are in the middle of the windscreen, while they could make it so they just go back when you turn them off, this is easier

Because the switch doesn’t directly control the wipers. It controls an intermittent relay switch in between the dash and the wiper motor itself. When you turn off your wipers, you tell the relay to stop, but the relay has already sent power to cycle the motor. The cycle is already running, but now that you’ve flipped your switch, the relay won’t start another cycle.

Serves multiple purposes: gives you variable speeds on the wipers, ensures the wipers always run a consistent cycle, and keeps your view clear by making the wipers end at their start position.

Wipers go back and forth between two positions, let’s call them left and right. Neither of these positions is the “stowed” position. There is one place on the cam that makes them go back and forth where if the motor reverses, the wipers are moved into the “stowed” position. When you turn the knob to “off”, they keep running until this spot comes around on the cam, and then the motor reverses to stow them. The place on the cam is not near either the “left” or “right” positions, because the load on the cam is high there and it might break if it was designed that way.

Ha! I don’t know, but this definitely happens. If I’m driving in mist or fog, and only want 1 wiper swipe, I’ll press the lever *down* (from the initial neutral starting position) for 1 quick wip-wap. I believe it’s the instance of pressing the lever down into this position, actually *past* the neutral ‘off’ position, that makes them wip-wap one time.

I mean you don’t want the wipers to stop in the middle of the windshield and block your vision, do you? They go all the way to the end of the cycle until they reach their original position.