Flat battery recharged - now key won't turn?

[Mechanicalincentives]

Hi there, new here, and been encouraged to post a new thread on this by a Senior Member. My lovely 200CLK (2.0 CLK auto Sport 1997) came from a lady friend who was upgrading just before lock down and so I took the car off her hands as a spare car during Covid - we are on the list so shielding and the car hasn't moved beyond moving it around on the drive since then. Looking in I realise we should have been charging it regularly, but I haven't as it seemed to be keeping quite happy and starting immediately all the time. Over the past week I have been trying to get her going again and she was lighting up, but not turning over so I got the charger out. (thanks by the way to other forums here - the boot lid was stuck but I got that sorted and have come back with another problem but haven't been able to find a similar answer).

So I've charged overnight and the charger says the battery is full. BUT, now the key which definitely was working before goes into the ignition and it's all locked up, nothing lights up, and I can't even turn the key? What can possibly be going on? Any clues much appreciated - I am missing the manual as well - though ordered it's a week away from arriving. All help much appreciated as I have insured and taxed her now and keen to get her running again. - Thank you in advance!

 

[Craiglxviii]

Firstly, hello and welcome!

where do you live? We may be able to help suggest a repair solution.

Secondly, have you checked the battery with a multimeter?

Can you open the bonnet?

What happens if you try to turn the key (only to position 1!) while the battery is still on charge?

Do you have an OBD2 code reader?

 

[malcolm E53 AMG]

First couple things to try are replace the key battery and check the existing car battery it should be 12.6V fully charged. If it’s an old battery I would change it anyway MBs don’t like undercurrent batteries (it may not be holding charge) it leads to all sorts of spurious electrical issues.

 

[Craiglxviii]

First couple things to try are replace the key battery and check the existing car battery it should be 12.6V fully charged. If it’s an old battery I would change it anyway MBs don’t like undercurrent batteries (it may not be holding charge) it leads to all sorts of spurious electrical issues.

The key should still work in the ignition lock even with no battery at all, the EIS has an induction coil to power the transponder when the key is inserted.
Unless the EIS has no power...!

 

[malcolm E53 AMG]

This article should help:

http://www.mercedesmedic.com/my-key-wont-turn-ignition-mercedes-benz-problem/

 

[Mechanicalincentives]

Firstly, hello and welcome!

where do you live? We may be able to help suggest a repair solution.

Secondly, have you checked the battery with a multimeter?

Can you open the bonnet?

What happens if you try to turn the key (only to position 1!) while the battery is still on charge?

Do you have an OBD2 code reader?

Thank you so much - and super pleased to have such a flurry of responses - it's brilliant to find such a source of knowledge.
To answer your questions
We are about 10 miles east of Stansted Airport.
Yes the bonnet opens
There is no movement at all on the key.
And I don't have an OBD but have been meaning to get a cheap one. I'll look up for recommendations and get one - any suggestions welcome

 

[Craiglxviii]

ICarsoft i980 is the basic one. Assuming your car has OBD2 and not 38 pin diagnostic (rectangular not round)

Id be looking to get the car recovered to an Independent garage if you have ignition lock problems.

 

[Mechanicalincentives]

This article should help:

http://www.mercedesmedic.com/my-key-wont-turn-ignition-mercedes-benz-problem/

Glad I am not alone here!! Thank you for that. Working it through.

 

[Mechanicalincentives]

OK, so I have charge in the battery but no sign of life whatsoever, and have tried a) Steering lock challenge, and b) battery change I haven't got the right battery in my stores. As it seems it should work even if flat I am going to call in the RAC as I have home start and I do have an independent garage I use if needed. I'll keep updated. Thank you so much for the flurry of suggestions.

 

[Reginald]

same issue what happened...my doors will open and lock so battery not completely dead....but key won't turn ?

 

[Tony Dyson]

Hi there, new here... So I've charged overnight and the charger says the battery is full...

Can you provide any further details of your battery charger such as;

1. Make and model No?
2. Programme of charge selected for the overnight charge?
3. Where (To what) did you connect your charger leads?
4. Was the battery still connected to your car during the overnight charge?

 

[onefortheroad]

same issue what happened...my doors will open and lock so battery not completely dead....but key won't turn ?

can you get ignition lights ?

 

[Reginald]

Hi no ignition lights as key won't turn at all...however, the lights come on and the main lights work so the battery doesn't appear flat ??

 

[joderest]

have to ask, have you tried putting key in ignition, then turning steering wheel slightly, then try turning key ?
It may well be the steering lock is a bit jammed.

 

[joderest]

also, is gear lever in park ?, may be the solenoid has got confused, try disconnecting battery, leaving for 30 mins and reconnecting, make sure lever is in park.

 

[Reginald]

Hi Guys

The key is dead as far as turning is concerned...wont turn at all...
I will disconnect battery for 30 mins tomorrow and see if that works and double-check car is in park...its hardly been used for the last few weeks and is very cold !!

Thanks

Charles

 

[Frontstep]

Methinks you haven't got a full complement of volts yet .
The RAC should be able to assist you with that as the season for battery issues gets underway they will be equipped oh and probably try and flog you a new battery!

Or test it yourself.

 

[oigle]

Sounds more like a steering lock problem to me. Have you hauled down hard on the steering wheel in both directions whilst attempting to turn key?

Ian.

 

[Reginald]

Thanks chaps ...it’s a plastic square key and from memory it normally clicks in and lights the ignition...have tried moving shell but no go....if I test the battery what voltage amp age should it show ....the headlights work on full beam so doubt the voltage is down ?

 

[Reginald]

Shell ...hard predictive text !