In my 1979 300TD wagon, I have just experienced a most perplexing problem. I turned on the wipers today in a brief rain, and they worked fine. When I went to turn them off, they would NOT turn off. The switch on the turn signal stalk works in the fast position and the normal position, but it won't work in the delayed wiper posion and it won't turn them off. I had to pull the fuse to avoid driving with wipers moving on my dry windshield.

I assumed the probem was most likely the switch, so I took a unit I had taken off a parts car and connected the big plug from it in place of the big plug from the one still on the car--but the results were the same.

I suppose there could be two bad switches, but I wonder if a bad relay could cause this problem. Anyone with any knowledge of this strange phenomenon would be most appreciated.

I don't have any experiance with MB wipers but an old Chevy truck I had had a switch in the wiper motor that turned it off.

You break the circuit at the wiper control and when the arms get to the park position, the switch in the motor shuts it off. May be out in left field here, but its worth a thought.

Ernie

Problem solved! It WAS the relay. For those of you interested, should you experience the same symptoms I did, the relay is located on the firewall behind and slightly to the left of the instrument cluster. It is easiest to remove it by taking the instrument cluster out. In my case, I solved the problem by tapping the relay on my work bench a few times, and the malfunction disappeared.