I have a '89 560 SEL with 107K miles. Just today I noticed upon startup that there was a ringing sound coming from behind the instrument cluster. At first I thought the stereo was not tuned to a station. When I put on the turn signal the ringing sound stops but restarts as soon as turn signal is turned off. Also, none of the instruments work. It was dark out when I checked the fuses but they all appear to be good. Any other suggestions? I think this is the second cluster in this car.

Finally, the wipers seem to short out when it is raining but works fine during sunny weather. Any suggestions for that would also be appreciated. Previous owner has partially stripped the motor output gear where it connects to wiper arm. You would have thought Mercedes would have made the wiper arm connector of a softer metal than the motor gear!

 

The same thing happened to my 1990 300E. Check your fuses.....carefully. The fuse that was "bad" looked good until I touched it and it opened. I think what might happen is the fuse opens, arcs a bit, and some carbon builds up to give a partial connection. LOL.