we had this fault the other day at first was intermittent then happened every time ignition on ....both front wipers and washers activate non stop had to pull fuse....well to cut to the chase it turned out to be on the wipers stalk there is an extra switch on the side for momentary well it seems due to wear this switch which activates when you pull the stalk towards you dosent return back to its normall resting position sits too high and shorts causing the front wipers and washers to run continuously we just put a thin plastic spacer made from a spray can top and fitted it where the little nodule / pip bit is on the stalk arm this made the slide switch sit correctly so at last fixed