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Marty, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 54962
Experience:  Bosch Certified Master Technician with over 35 years experience in the automotive industry.
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I have a Mercedes S280 W220 and the doors will not open or

close using the key fob... Show More
close using the key fob and the ignition will not turn at all. I have ordered a replacement key but still the same problem. Does anyone know what else this could be?
Submitted: 4 years ago.
Category: Mercedes
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replied 4 years ago.
Hi, my name is Marty. If your battery is fully charged and the key won't turn and the remote will not open the doors the problem is most likely a faulty electronic ignition switch (EIS). The EIS processes the signal from the remote to lock and unlock the car and also authorizes the key when inserted into the switch to allow the switch to turn. This sounds like a faulty EIS. Make sure that your battery is good first. Sometimes you can leave the new key in the ignition for 20 minutes or so then try it again and see if it will lock the car or turn in the ignition. If you have no success you will most likely need to replace the EIS.

Let me know if you have any questions.

Please note that your good faith deposit does not pay the expert for his help until you leave a positive rating. Please be sure to rate my service!

Customer reply replied 4 years ago.

Thank you for the quick reply.




Is there no possibility is could be a fuse or something simple like that


and if not any idea what it would cost to fix?

Marty, ASE Certified Technician replied 4 years ago.
Hi Noel, sorry for the delay I did not see that you replied back to me until just now. The EIS does get power from the battery prefuse and through fuse 78 in the cockpit fuse box. Whenever replacing the EIS the power and ground to the EIS should always be tested. Fuse 78 is located in the fuse box at the end of the dash. The battery prefuse is located under the right side front floor panel. That location is for a LHD US car. On a UK car it may be located on the other side. I've attached some pictures below. It is unlikely that this will be a fuse problem however.

Click here for the pictures.
Marty, ASE Certified Technician replied 4 years ago.
Hi Noel, I'm just following up with you on the Mercedes. Do you need any more help with this? Was my answer helpful?

Please let me know.