Mercedes: Windshield wiper problem, 1990 mercedes 300e, windshield wiper

Question
My 1990 Mercedes 300e has been sitting out side durring the winter. Just recently I have had the problem of my Windshield wiper coming on randomly with the wiper witch in the off positon when I start the car. This would continue unless I moved the switch on and off rapidly. While driving the wiper would come on randomly and I would have to mess with the switch or pullover and turn the car off then on. After figuring out that the car does not have a rain sensor I think it might be the switch or some other faulty electrical problem. Is there a step by step guide on how to fix this problem?
thanks.

Answer
Alex,
I suspect that the is a problem with the speed control switch on the wipers. If you can get a Mercedes repair manual you may be able to see how it is wired. Some libraries have tech manuals.
If the speed control is in the steering column, then you need to be cautions about working around the steering wheel, as the airbag has electrical connections. A wrong connection and the air bag could deploy and hurt someone.
The bag should be disconnected before doing any work around that switch.
Good Luck
Robert