c240 key locked : EIS or A1 module

M

Michel

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Hi,
This is for 2002 MB C240 4matic.
The alternator had a short cut and has been replaced.
This probably damaged something, as the battery went dead few times and we had to try jumps, then recharge, etc. Not sure if keys were always on at that time.

Now here is the result: the key (and backup key) will not turn (like blocked). Lights come, key is recognized, but will not turn to contact and start.

But, if you remove one wire from a black connector close to the battery (where the 12V plus goes and the Jump plug is, there are one large IN, in the center, and 5 medium OUT, 2 one side, 3 the other side. The one to disconnect is the one close to center, from the 3 side), then the key will turn. Just for a second. Put the Connector back, now it will be able to start and run as before.

If you remove the key, the engine keeps running, unless you disconnect the same wire above for a second.

I connected this wire to a plug that I can switch on off so I do not have to even open the trunk.

The only message from the console is SRS fault (I understand this is related to airbags, and has nothing to do with the key that will not turn, and the engine will not stop without the 'bypass' method), but this can wait I guess.

The dealer (receptionist) has no clue of what it could be. Tried to get the codes from his system, but said there was no connection at all.

In the mean time, I was able to get the message from my UITF scan :

4300 CAN communication is faulty
4314 Fault in CAN communication with control unit N73 (EIS control module)
4315 Fault in CAN communication with control unit A1 (Instrument cluster)
4316 Fault in CAN communication with control unit A1 (Instrument cluster)
4600 The voltage supply of circuit 87 has under voltage.

Someone else said could just be a fuse electrical relay.
I will check fuses tomorrow.
 

Cole@MBS

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Its a 203 being a C240 4 matic, stop disconnecting the battery would be my first advise!!!

That will cause more faults than you started with!!!
 

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As SAM above,,I would not do it,,all those codes could be a SAM going down
 
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Michel

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Fyi, with this added plug (ON to be able to turn the key, then OFF when you want to stop the car), I was able to use the car daily since 2 weeks. Have messages about Battery/Alternator and SRS, but else, seams OK.
 

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Do you know what the running voltage is on the car
 
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Michel

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When engine off, arround 12V, when engine on, 14V
 

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Does the ESP lamp go away when driven
 
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Michel

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Yes, as soon as the engine is on, the light ESP goes off. The only thing left when engine is on and car is running is message SRS, and sometimes battery/alternator.
 

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This means that the car is loosing contact with the ESP and SRS when the ignition is turned on, possibly a SAM cannot find them,,the same with the alternator
 
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Michel

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Thanks Malcom, It works with this new "plug option", but I still do not really know what exactly should be done to have it work without the "plug option".
 


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