This thread is a couple years old and having done countless cylinders since then I wanted to share some advice learned this week.

Make sure the cylinder is really the culprit. I was getting the tell tale signs of the failing cylinder so I ordered a new one from MB. After replacing it I still had the same sticking key symptoms. If I would have investigated before spending $100 I could have simply bought the new ignition mod for $28 which is the problem. Don't be fooled investigate before you buy.

What's an "ignition mod"? Ignition module? Most folks (myself included) would think EZL, not something related to the lock area...

:stuart:

Benz considers it a ILH, which is probably more confusing in the world of acronyms.

Can you offer more details on how to diagnose a bad ignition module...........how to eliminate the tumbler from the list of culprits? Does the tumbler need to be removed to make this determination?

Also, is there a photo of the ignition module..........is this the electrical portion of the "ignition switch"?

We all point to the tumbler as the culprit every time a member can't turn the key. This is likely not correct in certain situations.

Yeah, what exactly is this $28 item and where is it located?

Brian the tumbler needs to be removed and then using a flat blade screwdriver I could feel it "catch" when turning clockwise. The ignition module is the electrical part of the ignition lock housing. You are correct on assuming the tumbler is always the culprit - that's why I didn't hesitate to replace when the SDL ignition starting acting up. only to have the same problem with the new key and tumbler.

This is the part for the SDL
http://img.eautopartscatalog.com/live/M505032967OES.JPG

Sorry for the slight re-direct here. Has anyone used and had success with the replacement ign. switch available at ********AZ? I'm getting ready to do this job this weekend. Made by contitech. Link herehttps://www.***************/search/product.aspx?sid=ju35q5jdxjjemmivezbwv1ju&makeid=800016@Mercedes&modelid=1193004@240D%20&year=1983&c id=25@Ignition%20Parts&gid=4512@Ignition%20Lock%20%26%20Tumbler

The keys that come with them are alluminum or some sort of light alloy. I didn't like the fact that ignition and doors where different keys, sort of anal on my part but went to dealer and bought the right part.

Thanks John.

Well, that certainly presents diagnosis problems for new folks. I suppose that the tumbler should be replaced "on principle" and that the ignition module should be checked when the tumbler is out.

I hate to be a stickler for technicalities here, but "ILM" does not appear in any factory documentation I can find, at least for the 124 chassis. And "ignition module" is never used in reference to the electrica switch behind the lock cylinder.

The part shown in the photo above is referred to as the "starter switch" in the older print manuals, or in the newer CD manuals it's called "ignition/starter switch" or "glow/starter switch"... click here to see the PDF file. In the EPC, it is called "ignition switch". I replaced this switch on my '87 a year or two ago, because it would not always engage the main HVAC blower motor unless the key was turned back (CCW) slightly. The new switch fixed this annoyance. And that switch is a PITA to replace, even with the dash removed!

This is an ignition module (aka EZL ignition control unit, or ignition control module (ICM)).

:euro:

ILH not ILM Ignition Lock Housing. Ignition Mod was my word didn't intend to confuse, can't remember why I used that term last year.


Pffft

My bad. But there really is no ignition lock housing either. There is the steering lock (item #5 in diagram below), which is the main lock assembly... the lock tumbler (#26) goes in the front, and the ignition switch (#11) goes in the rear. But still no ILH.

:batman:

Thanks, this is vital and much appreciated information. Does it apply to the W123s as well?

:confused: Even Fast Lane Shows a Igntion Lock Housing - Remeber the pic is the ignition switch.

There are (at least) two different units for the 126, my '91 had the later 2-pin release like the 124 has, plus the ILH has the shift-interlock.