85 528e with wiper issues

I have a 85 528e that the wipers rarely work. Sometimes they work other times they do not. Sometimes when drive over railroad tracks they start up if I have them turned on and other times they stop. I am looking at a stalk problem, or maybe the wiper relay under the hood or something more perplexing like within the wiring. So does any body have any ideas of where to start looking?

Sometimes the dudes at the factory have had too many beers and put too much grease in the wiper motors. Once the contacts get grease on them, they don't conduct electricity, and then the wipers get psychotic.
Take the little wiper box off, drill out the rivets, open it up, clean it, put a tiny smudge of grease instead of a big wad, put it back together with screws, and it'll be fine.
Takes about an hour.
Look it up on mye28.com
4DF

had the same problem i changed wiper relay switch by fuse box they work perfectly all the time now