I had a problem with the wipers on my 123 wagon some time ago--they wouldn't shut off. My mechanic friend suggested taking out the relay and banging it on the work bench. I did this and the problem was solved!

The relay is located behind the instrument cluster--as I recall, there are a few other relays. Maybe a Haynes manual would tell you which is which. Anyway, if you can pull the cluster, you can see them easily. You could probably see them without pulling it, from underneath. They just unplug. Just a quick bang, not too hard, and see what happens.

I assume that you've checked the fuse first, of course.

Joe B.