Have Mercedes Questions? Ask a Mechanic for Answers ASAP
There are three common failures that need a Mercees xentry diagnostic computer to accurately diagnose. You would also need two remote keys for confirming the function of the ignition switch or steering lock. The remote key is the most common failure and it is always good to have a spare anyways. There are some basic checks you can do to ensure it is not a simple voltage supply problem. I would check fuses 27 and 22 in the front driver's side fuse box. If those are good, I would remove the large connector out of the back of the ignition switch and check pins 2 and 3 (The large red wires) for battery voltage. I would use pin 3 (large brown wire) for the ground so you can check that while you're there. If all of those checks are good, I would go ahead and order the remote key and try that. If the key does not solve the problem, the ignition switch or steering lock will have to be replaced at a shop that can program them. Let me know if you need any more information, thanks!