Same happens with my 2001 Marea (maybe something about the year?) Have lived with it for ages. Am told it's probably a relay problem, but before this (which was worse) occasionally my wipers, after they'd been on a long time, would refuse to turn off, staying on constantly on the slow continuous speed, including in the intermittent and off settings, and not stop if the lights were on. Sometimes they'd stop if you just turned headlights off but left sidelights on, but sometimes they wouldn't stop until you'd turned all the lights off. Either way that's not a lot of use if it's nighttime and it's stopped raining. That problem seemed to go away of its own accord thank goodness (after Fiat failing to fix it under guarantee - all they did was replace the stalk and then ran out of ideas). Probably a bad earth somewhere at a guess. But now I have exactly the same problem as you, which I've just got used to. Have become an expert at using the flick wipe for intermittent and to park them in the right place. It's become second nature. A little Italian individuality, but I've said it before: Magnetti Marelli should really have stuck to making the ice cream.
