Ignition key won't turn (electronic key) - Mercedes-Benz Forum

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post #1 of 7 (permalink) Old 01-07-2012, 08:33 PM Thread Starter
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Ignition key won't turn (electronic key)

The key will often refuse to turn. I've searched the forums and didn't find a solution. Thanks for your help. It is a C230 1998.

Please watch the self explanatory video on Youtube:

1998 C230 Key Problem - YouTube


Last edited by c23098peter; 01-07-2012 at 08:36 PM.
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post #2 of 7 (permalink) Old 01-08-2012, 10:18 PM
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I sometimes have a similar thing happen with my '97 C200, but in my case when I insert the key nothing happens, steering lock doesn't disengage or anything. If I stick my finger into the ignition slot and give it a wipe then all seems OK, but after this happens the engine starts for only a second before quitting. Next start no problems, whether your problem and mine are related I can't say, maybe it has something to do with dust in the ignition slot. Hopefully someone has an answer for us both.
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post #3 of 7 (permalink) Old 01-12-2012, 07:29 AM
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It may be one of three things. bad key. bad FOB battery or bad receiver. Replace the FOB battery (actually it uses two) as that is the cheapest solution. Looks and sounds like your immobilizer is releasing.

I have a 2000 C280 Sport. both of my black FOBs like yours went bad within a month after 11 years. Prior to the failure, they exhibited the same symptoms as your video shows. Mercedes will sell you 1 new chrome FOB for about $220. It has to come from them and you will have to show proof of ownership before they will sell it.

If neither of those steps solves it, then you are looking possibly at the key receiver, a more expensive proposition. Not heard of very many of them going bad however.
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post #4 of 7 (permalink) Old 01-12-2012, 09:28 AM
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Originally Posted by Tica View Post
It may be one of three things. bad key. bad FOB battery or bad receiver. Replace the FOB battery (actually it uses two) as that is the cheapest solution. Looks and sounds like your immobilizer is releasing.
I think that you will find that the fob batteries have NOTHING to do with the ignition key turning. In fact you can remove them from the key and it should still work!

The batteries just are for the remote central locking feature. The IR transponder in the fob is energised from the DAS infrared control module. So if the key refuses to turn to the start position, the DAS sequence is not OK.

On some models, the brake light switch also has to be operated for the key to turn fully.
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post #5 of 7 (permalink) Old 01-12-2012, 11:55 AM
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key fob needs to be replaced. there is a ring around the ingnition switch where you put the key. it detects when the key is within about 3 inches of the ring. the chip inside the key can stop out putting a signal out to the EIS ring, which cause the ign to stay locked.i have had this problem on my p[ersonal vehicle as well as multiple customer vehicles. if you can get your hands on a scan tool and can monitor the EIS module you can watch for a key signal when you insert the key into the ignition. if you do not see the signal from the key switch to ON, the key is bad.
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post #6 of 7 (permalink) Old 05-28-2013, 05:38 AM
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There are 4 electronic and/or mechanical modules that are synchronized for everything to work ok: 1. The key (electronic key); 2. The electronic ignition switch (eis, the place where you put your key in); 3. steering locker; 4 the central electronic circuit module.

If only one of them has a problem, the key will refuse to turn.
The first step is to check all the fuses are ok, if not replace all the burned with new and check if the problem persists.
Next step is to check connectors, and cables (not an easy task for non experts. Special tools are required like a multimeter; 12volt indicator; screwdrivers to remove covers; etc),
You need to assure that all the above modules are supplied with a +12volt line that is usually the first pin in each connector. Connect a the black wire from voltmeter to car's chassis that is the ground (-) and check with the red wire of the voltmeter to every pin of every connector. If casually there is a connector that has no +12v pin then it might be the problem; try to find out where the +12v should be and create a fused (5-15 ampere) bridge and connect it to where it should be. Check again if the problem is solved otherwise you need to check each of the modules separately to a specialist,
Each of the modules ca be reset and it might solve the problem otherwise you will have to purchase the defective module.
Their price is relatively high, starting with the fob key that is the cheapest and ending with the central electronic circuit that is the most expensive.
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post #7 of 7 (permalink) Old 08-26-2015, 01:28 AM
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my MBenz C180, 1999 model key fell down on a hard floor, afterwards the car has refused to start. What could have happened and what should I do?
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