Hello every one, I have a 2000 S500 with 100K miles. I owned it for about 5 years never had any problem. Few weeks ago it started doing a weird thing, if I drive for about 30 minutes or so, turn it off and leave it for 10 to 15 minutes it wont start again. The engine turns and everything but it will not start. I have to leave it for about 1 to 2 hours to get it to start again. I replaced the fuel filter, cam position sensor and spark plugs, and the problem still exists! My next guess is the crankshaft position sensor or maybe the ECM? Had anyone experienced a similar problem? Any help will be greatly appreciated. Thanks.

 

yes lots of problems with the crank sensor replace it just for general principle also check the M.E. control unit for codes this will help out alot. never seen a M.E. go bad in this way

 

Thanks for the quick reply. I will replace the crank sensor and post again.

 

Hello again, I replaced the crankshaft sensor a week ago and that took care of the starting problems! hope this will help someone else.

 

My 97 was intermittent like this for a long time finally when it got worse they figured it was the transmission fluid traveling up the harness, from the plug on the transmission into the brain (circut box of the car) when it dried it started again, you can see the fluid in the circuit board when you pull it out. this may not be your problem but they replaced starters , ignition wires and more on mine before they figured this out. Mercedes has apparently changed the plug design but I still have the problem. At this point dont know if its worth fixing.

 

Dylan,
easy fix, seal the whole transmission control module input connector after washing it up with silicone sealer and any fluid will drop off ones it would travel up on wires to plug.
You could also make barrier from silicone right above transmission connector and wash this plug ones in a while with electric contact cleaner and blow it of with compressed air.

 

Yeah that is an issue with the W140. Changing the plugs and rubber seals around the gear box is a preventative measure that good garages pick up and do, to stop the oil going through the harness and causing more trouble. If you have not had this done to your W140, get it done!

 

I would go to a Mercedes dealership and have them diagnose the problem with your s500. If it turns out to be the control unit then you do have options. The dealer will not tell you this but there is a place in Michigan that can replace your s500 ecm S500 ecm electronic control unit prices and S500 information . for about half the price of the dealer. They also program your vin and key.