W202 alarm / immobiliser problem??

[Ba Lad]

Dear all
Firstly a big hello to all of you and a great site I've come across!

Ok I have a problem...a very big problem.
My dear old mum beloved W202 has been with us since brand new. It's a C180 1997 W202 C class. A couple of days ago my mum went out shopping and came back to the car and car is completely dead. The car had been left open ax she had just popped into a local village store. When you insert the key in nothing completely dead. The red light on the alarm fob lights up. The central locking does not appear to work from the key fob at all. Normally when you insert key into ignition it will give you that electronic "zipping" sound with ignition coming on. I've had the car towed home since.
To let you know abit more about this weird problem.....the car battery is brand new replaced around a month or so ago....the spare key fob does not work as it packed in some years ago. Also the car has some on and off history with the alarm going off for no apparent reason at any time of day.

So to recap :
So no remote central locking
Door I/R central locking doesn't work
Physical key unlocks but not centrally
Re-synchronising doesnt work at all (point and press x2 and leave in ignition)
When key is inserted in the ignition, it does nothing. No response at all, no noise, no unlocked steering, wont turn.


I've had one guy come out to take a look who has quoted £500 and says it is the EIS + programming. OUCHHH!!!!

I am wondering could it be the alarm siren as I have been reading these can be a pain?
Can the alarm siren completely kill off power to car like this?

Or can it be immobiliser? Does the car normally turn but not fire with immobiliser ?

All help is much appreciated as it is a very clean car with 41000 miles on clock from brand new....
Please help.

Many thanks

 

[Dec]

The car battery may be flat and needs recharging.
The batteries in the remote fob should be renewed.
The alarm siren should also be replaced if it is the original factory fitted unit.

The siren could drain the battery if it were faulty.

More info required regarding the behaviour of the alarm.

Dec

 

[Ba Lad]

Hi there thanks for quick reply....the car battery is new....the key fob batteries have been replaced....
Could the siren be at fault and could the siren completely kill off power to the car?
The battery voltage with a meter across them is reading the 12V DC.....
It is a complete mystery what has happened here and the car is completely dead.
Not sure if it is the EIS or the siren?

Recently the alarm has been going off middle of the night and day for no reason....
I have read the siren batteries leak causing problem but cannot understand how the siren would kill off power to the ignition. The lights com on when switched on and when door is opened I get the bleeping warning that lights left on. Central locking button inside does not work.
Really need help with this one....

Any more help is appreciated ....

 

[Dec]

You should interrogate the spare key in case it might only need new batteries.
The batteries in the remote are to operate the central locking and have nothing to do with the immobiliser.
The presence of the remote fob in the ignition switch disables the steering lock and the immobiliser… PROVIDED the car battery has enough charge, it seems your battery would benefit from being charged.

The remote key fob could be faulty or as you mentioned the EIS, however a fully charged battery should first be tried before condemning the remote fob or EIS as being at fault.

The car is 17 years old and almost certainly the alarm siren will be faulty, it could trigger itself, because its faulty, for example it could flash the hazard lights all night long without any alarm siren sound, this would flatten the car battery.

Will internal lights or the outside hazards/indicators lights work.

Turning the metal key blade in the drivers door lock will lock/unlock the drivers door, it will not centeral lock/unlock the car.
The metal key blade is for emergency locking only and is used to open the car door/boot if there is no car power in the car battery.

Dec

 

[Dec]

Also, which fob do you have … Type A or Type B in bottom picture.

Your mum should be in possession of a FLAT key like the one in picture below, bottom left of picture, it would have come with the other keys when the car was new.

Dec
Picture source… Do I REALLY need to buy a new smart key? - MBWorld.org Forums

 

[Ba Lad]

Hi many thanks for your reply...I will fully charge the battery although I've got a good charge showing...and bearing in mind it's a brand new battery in there...I only replaced it few weeks ago...
I should've have mentioned the spare key packed up some years ago...spare batteries did not help hence using the spare....I have replaced the batteries in the key fob we have been using and again car completely dead....
Yes the internal and external lights work....
My question is can the alarm siren cause no power to ignition....
I'm completely at loss on this ...
Like I mentioned there is no ignition no power no nothing when key is inserted into EIS....

Another question is if I bought a spare EIS that comes with a matching key would it be plug and play?
Or would it need programming?

 

[Ba Lad]

Hi
It is a type B key.....

Yes the flat key opens the car but the key will not work electronically....
Does nothing.
Please help

 

[Dec]

I’m not sure about spare EIS so cant advise.
Open the remote and inspect the coil at the end of the key, if the key is dropped then the coil can be damaged so key wont work in ignition.
Disconnect the alarm siren, its located behind the front wheel arch liner on passenger side, there is a plug in the back of it, it could possibley play a part in the problem so best to disconnect it, its disconnection wont interfere with starting the car.

Are you sure all electrical connections are tight at the battery in the boot.
Also check ALL fuses, thats the first thing I should have said.

See also... Open Mercedes Key FOB (Old type) - YouTube

Dec

 

[Ba Lad]

Hi I've taken the pic bout and coil looks ok....red light flashes indicating sending pulse. But again nothing when inserted into EIS. I'm stuck on this one ...
Yes checked all fuses including auto theft and all are ok...battery connections are ok...I'm lost on this

 

[BlackC55]

If the key is ok it is very likely that the ignition switch is kaput. To check this it needs to be plugged into a Star. Dealers and specialists like me have them.

 

[Dec]

Unfortunately you don’t have a working spare remote key fob to test in the ignition so you still don’t know for sure if it’s the fob or the EIS that’s at fault, the problem is that if you replaced the EIS and it then transpires that it’s the remote fob that’s at fault.

Did the guy that diagnosed the EIS as being the fault use diagnostic equipment or was he guessing.

That car would have come with a Flat button less fob, pictured bottom left of picture below, its likely that it is with the User Manual and other documents that came with the car.

Try putting remote fob into ignition and then press the lock and unlock button individually and then the lock and unlock buttons together… just a shot in the dark.

If you view the end of the key through a digital camera and press and hold any button you should see a Purple light (no Red light in your case) as depicted in the video below.
[YOUTUBE]zQhwvjw29NA [/YOUTUBE]

Dec

 

[Ba Lad]

Hi
Erm...just read your bit about huge flat key....what is this used for?
ANC I cannot see any damage to the coil...and view through distal camera but no purple light....just yo clarify I have the slam keyfob without panic button in above pic( top left corner one)...
Please do help

 

[Ba Lad]

Hi also if I can't get ignition on how would I get it hooked up to star?

 

[Dec]

The huge flat key, you would carry that in your wallet, if you lost your 3 button key, then you could open the drivers door and disarm the alarm by putting it into ignition, that “huge flat key” will also start the car.

Your mum probably has this” huge flat key” key somewhere with the car documents, if she can find it will start the car…PROVIDED the EIS is not faulty.

You have fob Type B with no panic button (that’s American fob) you should see the Purple light through the screen of a modern digital camera or camera phone.
Do the test again in a darkened room, the absence of the Purple light would explain the failure of the central locking.

The central locking will not work from the central locking switch on the dash until the ignition is turned on, this is normal.

Dec

 

[Dec]

Hi also if I can't get ignition on how would I get it hooked up to star?

There is a socket under the bonnet the person doing the diagnostics would see to all that.
What is your general location?

Dec

 

[Ba Lad]

Hi thanks for all ur help so far...
Ok here is where we're at....mum mum found the Flat Master Key and......it started!!!!
So this must mean the EIS is ok and that the key is bad...
So next thing .... Where the best place to get a key? Mercs?
That right? ... I'm in Heathrow by the way

 

[Ba Lad]

Ok the purple light... There is definetly a purple light at end fob which can be seen thru camera

 

[Dec]

If you can see the Purple light I would expect the remote to work, however there could be something else wrong, perhaps it’s an intermittent fault. You could have someone like an electronics repair man take a look at both your broken keys internals, you never know, one of the fobs might be repairable, if you are lucky.

For a replacement remote key fob go to your local Mercedes dealer with ALL your car documents (V5) and proof of ID and about £225??? and the will make a new remote key fob, it takes about a week to process, I think the MB dealer will need to see the car as well so you might go with your mum to the Mercedes dealer to order the key fob.

The New fob will probably be of the Type A as in above picture as Type B is no longer in use as it’s not as reliable… as you have just found out.

You were fortunate to find the Flat Master Key; this will now do for your daily driving until you get your new electronic remote fob. Use the metal key blade to lock and unlock the drivers door and the boot … remember, the metal key blade only locks the drives door, the other 3 doors will have to be locked manually by pushing each door pin downwards.

You will need to show your mum how to unlock the boot with the metal key blade, it’s a little complicated, so you will need to refer to the cars User Manual.

You don’t need a spare key now that you have the flat key.

The alarm siren, as it is faulty, should be removed from the car in the next few days as it is likely to give trouble again in the future. In the meantime, if the alarm does go off, inserting the flat key into the ignition, this will silence the alarm.
The siren can be replaced for about £100 if you DIY or about £150??? if you get a garage to do it, I asked where you were as someone may recommend an Independent MB specialist local to you if you wanted to get the alarm siren fitted.

Also, lubricate the boot and door locks on that car as both are likely to seize up through lack of use, have the boot lid fully open when you lubricate the lock slot, see illustration below.

Dec

 

[Ba Lad]

Many thanks for the help so far....I had a look at the siren and it doesnt look a bad job to do...
I was wondering if there is someone out there who could possibly do a key or two cheaper as you are right Mercs want £220 for one key!!

Any ideas of a reliable indy who can do keys cheaper?
As I would like two keys....

 

[Dec]

Try this here… Mercedes key specialists- Need new Mercedes keys? Replacementmercedeskeys.co.uk
No idea on prices.

Remove or unplug the alarm siren for now BUT DON’T replace the siren until you get a new/replacement working remote fob.

Dec