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2005 C230 Kompressor Sport, 2004 SL500
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35 Posts
Discussion Starter #1
I replaced my key shell. The door locks and alarm works fine, but the key wont start the car. What did I do wrong? G oing to see if I can go back to the old shell.
 

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Registered
2005 C230 Kompressor Sport, 2004 SL500
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35 Posts
Discussion Starter #2
Changed back to old shell and still won't work. Well not sure what went wrong, thank god for spare key. Anyone have any suggestions??
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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19,452 Posts
Sounds like you may have broken the key so the IR emitter doesn't work. Use a digital camera or camcorder to see if the IR emitter is working. Camera CCD's can "see" IR light. Verify this by aiming your TV remote at the camera lens and pressing button. You should "see" the IR emitter light up. Now, point the key at the camera's lens and press the unlock button to see if the IR flashes. If not, then you have broken the IR emitter. If it does, then you broke the key's electronics. If just the emitter is broken, you may be able to fix it if you're handy with a soldering iron. If not, then the key is no good, except for RCL.
 

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Registered
2005 C230 Kompressor Sport, 2004 SL500
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35 Posts
Discussion Starter #4
Sounds like you may have broken the key so the IR emitter doesn't work. Use a digital camera or camcorder to see if the IR emitter is working. Camera CCD's can "see" IR light. Verify this by aiming your TV remote at the camera lens and pressing button. You should "see" the IR emitter light up. Now, point the key at the camera's lens and press the unlock button to see if the IR flashes. If not, then you have broken the IR emitter. If it does, then you broke the key's electronics. If just the emitter is broken, you may be able to fix it if you're handy with a soldering iron. If not, then the key is no good, except for RCL.
Thanks, emitter is working. I must have screwed up the electronics. I was extra careful. This is one expensive lesson. Thanks for the info.
 

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Premium Member
2005 CLK500 w/30K
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842 Posts
Thanks, emitter is working. I must have screwed up the electronics. I was extra careful. This is one expensive lesson. Thanks for the info.
There is a guy named drknight who offers an Ebay service to repair keys who might be able to resurrect this for you.

I think he ven has ads on this forum.

The plus is that it is often possible to upgrade to a metal key if you have one of the old plastic ones. The job involves removing the IC that has the car code and moving it onto the board of one of those useless USED keys from Ebay.

He has had great success doing it and I was able to do it for one of my keys too. For people in LA I am offering to do it for free to gain some experience.

Basically, if you have a dead key anyway, there is little to lose. You might have a look at the coil that power the key when in the ignition. It looks like a small piece of straw with copper wire wrapped around it. When you put key in ignition a magnetic field is fired up which causes a voltage to be induced in that coil, powering the key electronics to negotiate code. Keys will work with no batteries even in them. But that coil sometimes gets loose and then symptoms like yours.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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If the emitter is working, but the key is not recognized, that means that is rolling code has become de-synchronized and there's no way to fix that. Swapping the key's chip to another key won't work - it will still be sending the wrong sequence rolling code stored in its chip.
 

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Premium Member
2005 CLK500 w/30K
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842 Posts
If the emitter is working, but the key is not recognized, that means that is rolling code has become de-synchronized and there's no way to fix that. Swapping the key's chip to another key won't work - it will still be sending the wrong sequence rolling code stored in its chip.
Emitter working when button is pushed means the IR car unlock/lock circuit works.

Does not necessarily mean that the key talking to EIS circuit is working. It is powered separately. As a for instance, often the induction coil which powers this circuit breaks off (or breaks one of it's solder connections) from the PCB due to repeated drops. This coil could come completely off, the IR emitter would still light up to unlock doors but the part that talks to EIS would be 100% dead.

To sum up, just because door unlock circuit works is no reason to believe that EIS signal is present since it is a completely separate circuit.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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19,452 Posts
OK, that's possible, but I'll bet that the key has de-synced from DAS. It's not uncommon, especially if the coil is broken. Still, if the cost to try a chip transplant is negligible, it;s worth a try.
 
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