Mercedes Ignition Key Wont Turn

David Owner Metter, Georgia Posted   Latest   Edited  
2005 Mercedes-Benz C230 Kompressor 1.8L 5-spd (722.6)—WDBRF40JX5F709690
Key Wont Turn And Instrument Cluster Turns On When Key Is Inserted
Terminal 15 Remains On All The Time
B100c Terminal 15 Output : Short Circuit To Positive
B1025 The Input Signal Of Terminal 15 Is Not Ok

I am needing some help in diagnosing this Mercedes. The customer stated that the vehicle started cutting out for them while driving and then finally shut down. It seems a bit vague to me ... but from what I could understand from them, they towed it home and it sat for a few weeks and when they tried it a bit later the key wouldn't turn. It was towed into my shop and I verified the key would not turn. With the battery cable hooked up the Park indicator light on the shift lever area is lit up and it sounds like a few other electronics come on when hooking up the battery. When I insert the key into the ignition, I can here what sounds the electronic steering lock disengaging and the the instrument cluster lights up and turns on just like as if you were turning the key to the run position. But the key will not turn at all. Having the instrument cluster turn on like that seems to me like the key is recognized as ok. The steering wheel is not locked with the key in or out as far as I can tell.

See this screen clipping of datastream in the EZS/EIS module with the key removed. Notice that key inserted shows (no) and 504 Terminal 15 output shows (on) and all other circuits show (off).

EZS Data with key removed.

Next look at this screen clipping of datastream in the EZS/EIS module with the key inserted. Notice that key inserted shows (yes) and 501 Output Terminal 15C changed to (on) and also 505 Output terminal 15 changed to (on). At the time the key is inserted the instrument cluster turns on and the steering lock sounds like it disengages.

EZS Data with key inserted.

Also see this screen clipping showing Start Enable and EIS/EZS turn enable issued information. The turn enble is (no) and the start enable from the Electronic steering lock is (yes). The coil for energy supply of transmitter key does switch to (yes) when key is inserted and then soon switches to (no).

EZS data with key inserted showing Start Enable and EIS/EZS Turn Enable Issued

See the initial code scan here.

See the code scan after clearing codes here.

Quite a few of the modules show an issue with terminal 15 power circuit. Is the EZS/EIS module responsible for this circuit remaining on? I did not check with the customer yet to see if they have a second key. From my research it seems to be an issue with the Electronic Ignition Switch or the Electronic Steering Lock. Is there a way to pinpoint which one is the culprit? I haven't done many other tests other than what you see here with the scan tool. The DAS modules all appear to be initialized according to the datastream.

Thanks in advance for your help. 


Nicholas Diagnostician
Brooklyn, New York
Nicholas Default

Hi, First try another key if available. Then you need to check the BUS signals, power and ground at the EIS module. If all is good and only one key, replace EIS and get one new key. I have only had a few times it was not the key or the EIS, and testing the bus signals, power and ground helped me determine the direction to go in, Good luck.

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Sisco Owner/Technician
Mendon, Vermont
Sisco Default

Between your 619/620, I would say that the Customer does have another key, try that first (easy stuff first). IIRC, some of the CAN circuits will not power up unless the key is turned. Have replaced EZS for same issue in the past. BTW, MBUSA has made it real tough on sourcing TRP (Theft Relevant Parts), NASTF LSID a must.

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David Owner
Metter, Georgia
David Default

I had seen that too. It does look like this car has seen more than one key. I just haven't asked for a 2nd key yet.

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Solaman Owner/Technician
Chaguanas, Trinidad and Tobago
Solaman Default

Hi,If the ESL isn’t locking when the key is removed,then the it seems to be faulty,on your Live data stream 891 Motor Electronics start enable is saying no,the return signal from the ESL was not received to the EIS,hand shake is missing,you can buy a W203 Emulator and temporarily by pass the ESL,they are very cheap on ebay,under a hundred bucks,at least you can rule out the ESL and the key

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David Owner
Metter, Georgia
David Update

I am posting an update here to my testing and diagnosis on this Mercedes. First of all many thanks to Samuel Reed on IATN for his detailed help. You can read his help on this link. Mercedes IATN link I do not have the vehicle fixed as of yet, but I have it diagnosed and am waiting on the new Signal aquisition module arrive. The embedded picture below has the details of my tests and the

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David Owner
Metter, Georgia
David Update

Hello to all, I installed the new SAM (Signal Aquisition Module) and coded it and the key turned immediately. The car started and ran normally. As I had said in my update the SAM module had been internally corroded and caused circuit 15 to stay on all the time. The EIS (Electronic Ignition Switch) did not like to see circuit 15 on since the EIS is responsible for turning that circuit on with

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