Ignition lock / switch
 

Today I had the no-start issue permanently. Previously it was one of my keys which was prone to just turn in the ignition, but nothing happening. They key could be turned around endlessly. Yesterday I found the car with a flat battery. Really flat, no lights turned on, not even dim. Today I found out why, seems the car didn't fully turn off due to ignition lock / switch issue. I can now turn both keys around and around without any effect.

So time to take the whole thing out. Strangely, once out of the car I couldn't replicate the issue. My internet reading led me to believe it would be the mechanical part which failed. New one quoted by the dealer comes in at E 220. Not really cheap.

I wanted to make sure this is the actual issue, so tried to replicate the problem. I can now do this (without the switch attached, so ruling that one out as the source of trouble) by turning the key back quickly to the 0 position (or slightly behind, at least to the mechanical stop). Then turning forward again just spins the key and I can see that the part that should rotate the switch doesn't turn.

Next step, taking the key barrel off (again). This looks quite clean and I found no way to replicate the endless turns when I keep the housing fixed and turn the key. The lock side also couldn't do that. So I figured it might be the whole key barrel spinning in the lock mechanism.

Even further inspection revealed that the parts that the barrel connects to can in fact be pushed in when in the '0' position. I figured that if it would not spring back, the barrel would just turn because it connects to nothing. That part I was also able to replicate. But the barrel back on, pull the rod on the switch side and voila, the barrel keeps spinning.

So on the positive side I have now confirmed that my issue is the mechanical ignition lock assembly. And I now understand why the switch itself can cause issues which seem mechanical.

Next step: take the lock apart.... :D

On to the disassembly. By removing the nylon snap ring the inner works can be pulled out. This is what you get inside:
Attachment 23803

And the inside of the housing (showing the actual steering wheel lock deeper down with a spring etc.)
Attachment 23802

From this I didn't find any loose or damaged parts. What I did find though was grease which has almost turned solid. That's not really nice. Also there is a little spring pin at the bottom of the assembly which I think is the main spring force to keep the key barrel connected.
Attachment 23804

his pin and spring were also very very sticky. The pin did return, but slowly. So I took it out, cleaned the hole with brake cleaner and did the pin and spring as well. New grease on and re-inserted. I did the same on the other parts (the housing as far as I could as I didn't want to use brake cleaner on that with the wheel lock parts still in place). All new grease and then assembling it.

So far I now can't replicate the endless turns anymore. The tricks I learned to get me into that mode no longer work. Besides that, the wheel lock pin now really snaps out when I remove the key. Previously it would slide out slowly.

Overall I feel this could have solved my issue. I will get myself a new ignition switch as well as the old one does look a bit dodgy, but will keep the whole mechanism and try it out.

Today I received the new ignition switch. In different articles it was mentioned that 4B0 905 849 is the upgraded replacement switch. However, this one does not fit, the top of the housing is different. I'll add a picture later. So I now ordered the original number 4A0 905 849 which is due to arrive tomorrow.

Just for reference, the number on my ignitiion lock mechanical assembly is: 996 347 017 04