My 96 300D engine will stop running for no apperant reason while I am driving it. Mercedes says they cannot find anything wrong! It has 75,000 miles on it, any suggestions where to start? Ken

 

K40 relay module located on the passenger side module box under the hood. It is under a cover with 4 screws. It has fuses and relays on it and supplies power to engine control unit. I have also seen crankshaft position sensors fail on the diesels, not as common as gasoline. With the age of the vehicle, it would be a good idea to replace both.