C240 2001

Since the weather turned cold recently my 2001 c240 has been giving me issues. When we have a cold morning neither of my Smart keys will open remotely lock or unlock the doors and then if I open the door manually(with metal key) and insert the smart key into the iginition it will not allow me to turn the key to position 2. If i wait till temps warm up the smart key will unlock doors and then key will go to second position.
When this issue is happening all interior lights, radio etc DO work. Also to note, when vehicle is cold smart key DOES blink red light when attempting to lock or unlock. Car also does light redlight on shifter (P,R,N) when key is inserted into iginition, so to me that says it sort of acknologizes that it has been inserted but will not do the handshake to allow it to move to second position.

We have checked fuses, checked the battery

I have asked around and some think this may be a bad relay. I would like to check this next. I cannot seem to find a Relay chart or info on where it may be located. I am thinking that it is having an issue that is enhanced by the cold weather.

So does anyone have any info on where this relay might be located? And which it might be, is there a relay that both the iginition process and the electronic remote lock/unlock feature share?

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2001 c230

OK, so the remote lock/unlock doesn't work, and the key will not turn when inserted into the igniion switch, and, this happens no matter which key you use? Either you've got two bad keys (not likely), or the Electronic Ignition Switch (EIS) is no good. The problem is most likely the EIS, though. After all, what are the odds of both keys failing in exactly the same way, at exactly the same time.

In case you're wondering how a bad EIS can cause the remote locks not to work, the answer is simple. The EIS validates the signal (either radio frequency or infra-red) sent by the smart-key.