Rear wiper comes on all the time

Hi guys i wonder if you can help me?

My rear wiper comes on all the time even when its switched off. I have taken the back panel off and the foam lining is damp but there does not seem to be any leaks from any of the pipes. Has anyone had this before who might now what it could be? seems to be quite a common problem with the rear wiper but i cant seem to get to the bottom of the problem or find it on the forums here.

Thanks

Thanks Khufu for your reply, i've noticed that the stalk click's when moving backwards and forward and also the relay you mentioned also clicks, sounds like the click comes from the area where the fuse's are at the bottom right side of dash.(hope that where you meant?)

is there any thing else you can think of, or a way of testing the stalk.

Once again thanks ever so much for your help.