if anyone has a 1993 or older mercedes, any model, and the cruise control doesn't work, or works intermittently check into this:

I replaced the speed transmitter on back of the instrument cluster and it fixed the problem. I had read this on an old forum post from years ago but it didn't mention the other things that this part will fix. Other devices linked to this part are the climate control, the fuel injection management computer, and the radio speed dependent volume control. If the volume raises and lowers automatically at all times your speed sensor is good, but if it raises and lowers only occasionally or never then the speed sensor is bad. The climate control relies on the speed sensor to know when to turn on the the auxilary water pump.. like when the vehicle is traveling at lower speed.

the main problem when this part fails is that the car will stall occasionally while coming to a stop. If your car stalls while coming to a stop but immediately starts back up this is probably the culprit. The mixture control recieves input from the speed sensor to tell it when the car is coming back to an idle situation (coming to a stop) and if there is no input the idle fuel mixture becomes to lean when coming to a stop.

The part is also called "Hall-effect" speed sensor. It is located directly on the back of the instrument cluter behind the speedometer and is held in with one screw. Here is a picture of it:

[IMG]local://upfiles/14165/AE0452AF76344671B9DBE770B03DA937.jpg[/IMG]