Perhaps someone will find this useful...
My ignition key would not turn. It's the infrared key for a 2002. When the key was inserted , it unlocked the steering column, and the dash lit up normally. Both keys behaved the same way. It happened the other day, but fixed itself that time (removing / reinserting the key). Today it wouldn't correct itself.
I saw various suggestions, but for slighly different symptoms. Then I found the suggestion of inserting the key and simply leaving it in position 0 for about 30 minutes (I waited an hour). Then I removed the key, reinserted it, and the problem disappeared.
It took hours of surfing to find this solution in a non-W210 forum (https://www.benzworld.org/forums/w212...-ignition.html
). And I didn't see anything in the Common Problems / Stickies. So I thought I'd reference it in this forum.
I don't know what triggered it for me. The forum suggested that the owner might have locked the doors with the windows down, then reached in and unlocked it manually without using the remote or key.
Naturally, before I found this suggestion, I removed the ignition switch from the dash, thinking I might find something broken inside. It wasn't difficult to remove once I fabricated a tool to remove the front escutcheon. I used a piece of inch-and-a-half sink drain (thin metal), and I cut four notches in one end so it looked like a Rook (chess piece). It worked fine. I then disassembled the switch, but didn't see anything wrong. I'll attach some pics in case anyone finds them helpful. Splitting the two halfs of the plastic housing was pretty easy by using 9 sewing pins to hold each of the clips open (see photos). However, you'll quickly realize that you probably don't want to mess with the innards of the EIS...it contains 3 circuit boards and about 9 Integrated Circuits!
BTW - I also tried calling the dealer. The service receptionist suggested this might have a simple solution, but then transferred me to a service manager who insisted I'd needed to tow the car in...and to expect an $800 bill. Only later did I find this recommendation...and I'm not too happy that the dealer didn't suggest it. Who knows, maybe the problem will reappear tomorrow...and maybe the dealer was right. But having practically given my first born just to get a spare key about a year ago, I dreaded the notion of getting the EIS swapped!
Thanks again to all you good folks on this forum that have helped me address this and other problems on the Benz.
Here's how I inserted the 9 pins to hold the clips apart, and then the two halfs of the plastic housing pulled apart easily.
The bent sewing pin in the jaws of the hemostat is touching a "catch" that blocks the key from turning. When the catch is moved by a solenoid, it lets the key turn. I didn't see anything preventing the catch from moving. And the solenoid registered 16.5 ohms DC resistance...so it seemed like the solenoid was intact. I was tempted to break the catch off so the key could turn unobstructed, but I hadn't yet reached my wits end:
This next photo just shows how complex the EIS is:
Here's another view with the key inserted: