Hi everyone, I'm a newbie to the S-Class, having run an E220 for a year and driven the 2014 S350 Hybrid!!
Got in the car to go to work this morning and the ignition key will not turn.
It unlocks the doors, and the seat and steering wheel positions set themselves OK, but the key doesn't want to turn at all.
The key is the sort that doesn't have a metal shank or lock tumblers.
Need some advice please.

 

A weak car battery is the usual cause, it has enough juice to turn in lights etc , but not enough to allow the imterlock to release so the key can turn

 

Thanks, one of the other contributors said the same thing, and as the day became warmer, the battery revived and problem solved! Thanks fro your response

 

I charged the battery for 24 hours and also had it tested. No problem with battery and 12.24v this morning.
But key still locked this morning, remote works and key is recognised (seat and steering column positions return to memory preset)
Grrrr... so frustrating!

 

Sometimes the battery may test good but still doesn't have enough power. I personally experienced this problem. Mine ended up being a dead cell in the battery. After installing anew battery the problem was resolved.

 

Its likely a weak battery. On these cars you need a strong battery- it may be strong enough to perform some electrical functions but not all.

Many times a battery will test good but still not be enough for these cars.

 

Hi everyone... Well, a little lubrication of the switch with aerosol PTFE in a spray which is a little like WD40.
Key now turns easily, BUT...
Engine doesn't crank, and this time it is not the positioning of the gear selector!
Everything lights up and heaters light and go out.
However, there are three red flashing lights on the suspension buttons when the key is turned... these were not evident before!!
Battery has been professionally tested and charged for 28 hours @4A; currently shows 12.24v when idle.

 

Ptfe?


You'll be needing an eis now

 

Seabridgeman:

Congrats on your new toy!

Before spending alot of money (as EIS's are expensive), I'd give more heed to the battery/charging system. A 12v car battery standing should never be less than 12.6v (see http://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery) and whilst charging (idling), you should be seeing as much as 14.+ voltages. With a battery at 12.2v, it would suggest to me that there is something else going on. I would suggest that the existing battery is very weak. Out of curiosity, what is the battery voltage without the car running but with the ignition on?

Once you have that solved (could be a bad meter), then go for the EIS if the problem is still there. But around this time you might want to have a dealer involved as the costs will escalate quickly if you don't have a good grasp of the problem.

Just my opinion

Tower

 

Tower, I agree that the battery voltage with no load other than the standing load of the completely idle car electronics should probably be more than 12.2v.
I will probably be buying a new battery shortly to make sure, because an S-Class is mighty heavy to push home!
However, yesterday, 6 hours after a full 26 hour charge, the voltage was 12.45v, and still the switch didn't work and the engine would not start.
Tonight, I went and bought some contact cleaner and squirted four blasts into the EIS.
Left it for 10 minutes and then tried to start the car.
I am pleased to say that everything worked like a dream...
I will leave it overnight with no extra charging and see if it works OK tomorrow morning.
Thanks for the interest.
Clive

 

Okay, but you are missing the big point. If the car is running, the alternator should be pushing all the electrical needs of the car. For it to do it, it has to be pushing a voltage higher than the battery quiescent voltage. Normally that is in excess of 13+ volts even with a fully functional new battery. Not 12+/- volts.

I'd be checking the battery first. If it were me, before starting the vehicle and after it has set undisturbed for at least a few hours, what is the voltage at the battery. If its less than 12.6v, especially after you have been charging it for an excessive length of time prior, its done or just about ready to be done (note, don't charge it and then give it a test, rather charge it and then remove the charger and after 6 hours come back and check it.)

Secondly, test the battery voltage while you are trying to start it. If the voltage drops below 10v again the battery is too weak.

Lastly, check out the charging system. If the alternator can't push 14v, especially right after starting the vehicle, it probably means something in the charging circuit is kaput. This could be the reason the battery is misbehaving as it has never gotten a full charge and approached the float level it's expected to see. Result over time is a pooched battery.

Good luck.

Tower

Note: a battery with a level 12.2v +/- at rest (new battery by the way) would indicate that you have about 1/2 of the capacity (amp-hr) as a fresh newly charged battery. Yours is less than that as you said the 12.2 volts was when the car was running.

check out http://www.mmbalmainauto.com.au/PDF/..._batteries.pdf
for an explanation

 

Thanks Tower, I came to the same conclusion yesterday and ordered a new battery (although when I said there was 12.2v with the car idle, I didn't mean "idling" with the engine running!! With engine running it was 13.98v free and 13.74 under load (A/C and headlights) 11.76v whilst cranking.
Now it has been 48 hours since a full 26 hours 4A charge and the voltage is 12.18v... dropping to 11.7v as soon as the ignition switch is turned on, without cranking!!
Quotes for a new battery were £175 by Halfords and I eventually bought an Exide 100Ah 900A 017 from the internet, to be delivered tomorrow delivered
at £89.99, and that with a 4 year guarantee!
We'll see what happens then... will record it here tomorrow.

 

Seabidgeman, I'm on the other side of the pond, but from my experiences, I would never buy another exide battery. Interstate or Deca for me. You pay more but the batteries last a whole lot longer, again in my opinion.

Best of luck

Tower

 

Ah well, I've now fitted 26kg worth of new HD battery (weighs half as much as my gf) but twice as unruly! Difficult to get battery into position, but succeeded.
Keys turn intermittently, sometimes stuck in position 0, sometimes turn to acc, then heat, but nothing on the start position.
Only occurs in the morning, often starts by lunchtime!
Two potential solutions - new EIS (£375 trade + fitting), or gearbox control module (Gearbox is telling EIS that it is not in Neutral or Park.) The latter from a Merc specialist.

 

New Battery, new batteries in keys, can now turn keys in ignition switch but they only start the engine when the weather is warm, or the engine has already been running. A quick go with my iPad and a diagnostic unit in the OBDII port gave the following fault codes: (Stored) P0800 Transfer Case Control System (MIL Request) and (Pending) Drive Motor "A" Current Low... anybody any ideas??

 

And... when the ignition switch is turned to on position a red light in the suspension height button and two red lights in the damper control button flash.