The electonic ignition switch (EIS) in my 1998 E300 had started to make a random clicking noises a few months ago that sounds like a relay opening and closing. By lightly jiggling the key while in position 2, it clicks rapidly. It did not seem to have any impact in starting the car so I have been ignoring it up until now. I'll come back to this in a second...

When I brought my car in for an inspection last week the mechanic failed it because the horn would not work! After cleaning the spade terminals and checking the relay, still nothing. The next morning after starting the car I tried the horn and... success! Then, after driving to work and parking the car I tried it again and... nothing.

After a few days of trying to correlate the horn function to something (time, vehicle temperature, etc.) I finally stumbled onto what is going on. If I slightly push the key in the ignition in the 12-o'clock direction and hold it, horn works great. Conversely, if pushed in the 6-o'clock direction, no horn. I'm assuming the PO had a heavy keychain hanging off the key.

So, I betting a new EIS would fix it but I want to check with the experts on this board first on a possible DIY. Can the innards of the EIS be extracted and cleaned? I've had quite a few cases of electrical components on working properly on this car and every one of them was easily fixed by cleaning some contacts (side marker lights, fog lights, radio volume knob, and combination switch).

Any advice is appreciated.

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Scott C.

2006 E320 CDI (120k miles)
FOR SALE: 1998 E300 Turbo Diesel - Black w/Tan Leather - Euro delivery (236k miles)

Change the battery in your remote before you spend lots of money

That battery only powers the door locks and has nothing to do with the ign start sequence.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Really? I thought these unnecessarily large keys had a transceiver in them, complete with electronic eye in the "key" end, which communicates with the car during ignition. Unless there is some inductive current, I'd guess the battery in the key has something to do with that sequence? I'm a newbie, I admit, but I'd like to know more about this...

Cheers, John

As stated the battery is only for the remote. The DAS (drive authorization) function does not need a battery. One of the keys that originally came with the car was a wallet version that just looks like a hunk of plastic an 1/8 inch thick. It will not do the doors but will start the car.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

You're correct, the "smart key" is powered inductively, by the EIS. You can remove the batteries from the key, and still start the engine.

Thanks for the explanations. Makes sense...it would suck to have a dead key battery and be unable to start the car. Then again, I've seen worse designs in the automotive world...

Cheers, John

(Bump)

Someone out there must have had their ignition switch apart. How is it done? Does the silver ring need to be unscrewed and if so how do you get a grip on it to remove it? I have a subscription to AllDataDIY but all it says is to "remove coil (L11) for transponder from lock cylinder".

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Scott C.

2006 E320 CDI (120k miles)
FOR SALE: 1998 E300 Turbo Diesel - Black w/Tan Leather - Euro delivery (236k miles)

I am bumping this again since I am feeling fairly lost on this one as I do not want to damage my EIS as I understand that they are fairly expensive and require programming at the dealership ($$$). There has to be some visible contacts that can be accessed once the lock cylinder is removed.

I've attached a closeup picture of my EIS for reference. Does the "bezel" have to be removed in order to extract the lock cylinder? Or, is the bezel just there to secure the EIS to the interior panel?

Any help is greatly appreciated.

Attached Thumbnails

 

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Scott C.

2006 E320 CDI (120k miles)
FOR SALE: 1998 E300 Turbo Diesel - Black w/Tan Leather - Euro delivery (236k miles)

I didn't even think about the key positioning. My horn, sunroof, garage door opener and auto door locks stopped working when you start the car. I read this post and put the panic button at 6'oclock and everything worked. I also tried the spare key and it did the same thing (panic button at 12'oclock horn etc. not working but panic at 6 things worked fine. With the key chain hanging it's not the natural feel to put the key in with the panic @ 12'oclock. Does this have anything to do with the ignition switch?

Did anybody help you with how to remove the ignition switch? My switch clicks really bad but if I push up on it the clicking stops. I took apart everything under the dash to get to the switch but I stopped before I broke something. It would be great to get some advice on how to remove the ignition switch. I can move it slightly from behind. If I could get it out I know that it's something simple. Please help if you can.