Hey everyone,
Sorry for the lame heading. I'm on my way from Florida (home) to New York (school), and made a detour to Alabama. I get to Alabama, turn off the car, eat some food, and return to my car only to find that the smart key won't turn in the ignition.

I'm driving a 2004 E320 with only ~35k miles.
The smart key will unlock the car, trunk, panic, but it won't turn in the ignition.
I can turn on the radio, and from the digital menu/console in-dash I can only see temperature.
It's colder than the car has probably ever seen before, but it's only around freezing. Nothing extreme.
I called the dealer and they had no idea what was wrong. I'm hoping someone has seen this problem before or has some idea as to what is causing it. I need to get back before classes start. -_-

Thanks.

 

Also, there have been no battery issues in the past, and the battery to both the smart key and the car seem fine.
I've been searching the web for the past few hours, and I haven't found anything really similar. Most other smart key issues involve dead batteries or leaving the smart key in the ignition for extended periods of time.

 

Oh, and this isn't just because the steering column is locked up and I need to move it one way or the other to turn the key. That was the first thing I checked.

 

Hi David,

Mmm.

A pattern is appearing. Smart keys and failure to turn when COLD appear to be linked somehow.

Fact. The batteries in the smart key have nothing to do with the key NOT turning. Different systems working here. The batteries operate the PSE via the DAS which in turn unlocks the doors

The smart key gets it power to achieve security "handshake" (i.e. correct key) thru an inductance ring which is part of the EIS Electronic Ignition Switch.

A solenoid permits the key to turn once the handshake has been achieved.

So no turn = no handshake or possibly the solenoid (fundamentally a mechanical device) doesn't like the cold or possibly some electrical aspect of the solenoid is preventing it from operating.

EIS change, key recode is not a roadside repair.

ONLY advice from 3000 miles away is to "warm up" the key AND the area of the dash where the key inserts. Careful not to get the area to hot and it will take some time for heat to "soak" into the mechanism.
No idea how you can achieve this unless you can get the car into the warmth somehow.

Good luck.

Let us know how you get on.

What I should like to knoe is whether the inductance ring performance drops offs in low temperature (unlikely since the car will have been tested extensively in cold climates) or more likely that the mechanical aspects of the solenoid don't like the cold after a number of years in service.

Maybe there isn't a pattern here and you have just been unlucky....however I sense there is one.

Stuart

 

Update:
I warmed up just the key, and the key turned, but the engine didn't turn over. The console said to remove the key. Which I did, and now the steering column is unlocked, but I still can't turn the key in the ignition. I called back a dealer with the new symptoms, and they told me to 1. Jump the car and try again because the battery might be weak. or 2. The EIS is bad, and I'd have to get it replaced.
The nearest dealer is about 45 minutes away (~250$ tow bill) and they said the EIS would run me about 900 dollars.

 

I go along with the dealer comments.

Flat batteries at this time of year are very common. Either battery reached end of life or alternator not charging correctly.

MB's are very sensitive to seeing the correct voltage.

EIS is expensive and you need to eliminate other suggestion first since it may not be the EIS.

Go for battery voltage first.
Voltage with ignition OFF?
Voltage whilst cranking?

Stuart

 

Haha
You beat me to it. I did some testing since I'm already late for school, and it seems that the ignition won't turn when voltage is about 11.75v or so. I cranked it above that point. ~_~ Is it just me, or does that seem to be a really high reading for the EIS to crap out? Batteries drop below that because of the cold all the time.
So the car is jumped and running in the parking lot.
I forsee having my roommate jump me seeing as it's 22 in Ithaca, NY and today is a warm day.

Thanks for all the help, I'm off to New York!

 

Once a bateery goes below 12.5v it is scrap. Period.
You may be able to recharge it but chemical changes mean that at ANY MOMENT it will let you down (internal short type problem) and of course at the worst possible tiume,.

OK 11.75 is the threshold voltage. Where did you get that info. MB dealer?

ECU processors give unpredictable operations when operating below design voltage so the circuits are DESIGNED to shut down at a threshold voltage.

So I can now confirm there is a trend that failure to be able to turn the key IS linked to temp but also to battery voltage.

next guy with this problem will be asked to verify battery voltage first.

Incidentally I used to test cars in Finland / Canada and we used to look for -40 deg C = -30deg F (I think)

A good battery should always be in excess of 12.5 and when on charge should be about 14.5v.

Stuart

 

Yeah, I'm in New York now, and I can't start the car again. I'm going to try to take the car to the dealer tomorrow assuming I can find someone to jump me in time to get to my appointment at the dealer. It's a 2004, so it's not unexpected that the battery is bad is it?

I found 11.75 because I was at an Auto Store, and they hooked a voltmeter up to the car. It wasn't starting at around 11.75. Very imprecise estimate.

 

Your car is five MYs old and it is the original battery (assume it is based on your mileage). The chances of the battery finally dying is very high. A car that age with low miles has a higher chance of a dead battery than the same car with a lot of miles. Every battery suffers battery degradation as the temp drops(up to 40%). As you drove north the battery weakened to the point where it could not maintain a charge.
Today, in Toronto, it is the coldest day of the season (so far) (-15C or 5F) and the number of cars with dead batteries increases significantly.