Remote locking fob needed to be synchronized

Twinwasp

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I unlocked my 1997 C 250 turbodiesel normally, took her out, but when I tried to lock her, the fob woulodn't work at all. Back home, I checked the batteries in the fob and they seemed fine, but still no locking. The spare locked her normally. I changed the batteries in the first fob but still no locking. So I looked in the book and synchronized the fob per the instructions. First no response, then normal locking again.

Does anyone know why the fob might have lost its synchronization please?
 

John Laidlaw

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Because the batteries had failed...
Be careful to use decent branded batteries not the pound shop specials- those will cause problems
 
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Twinwasp

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Because the batteries had failed...
Be careful to use decent branded batteries not the pound shop specials- those will cause problems

Many thanks John. Curiously, when I tested the fob with the existing batteries, the red light came on to suggest they were fine. I put them in last November and they've had very little use since I don't use the car much. But I'm sure you're right. The replacements just fitted are Duracell and I'll make sure I stick to those or similar brands! Thanks again.
 
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Twinwasp

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I wonder if I can call on your expertise a bit more on this one please John:

The book says I can unlock using the key in the door lock if the fob fails. Would this set the alarm off - and would it unlock all four doors, boot and fuel cover? I thought I should ask before trying it and possibly waking up the neighbourhood!

Many thanks in anticipation of your further help John.
 

television

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If any key is locked via the electronic key, then the alarm is set up providing it is all working ok. If you undo the car via the metal key, then the alarm will go off and pop the key in the ignition, then all clear again.
 
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Twinwasp

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Oh fine - many thanks. If I ever have to unlock with the metal key, I'll make sure I put it in the ignition immediately. Presumably I also have to switch on to "position 2" as I did when synchronizing the remote fob yesterday.....

Presumably unlocking with the metal key will open all the doors / boot, fuel cover?

Further thanks.
 

John Laidlaw

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Sorry was driving home and just saw this, but you've been helped by 'the boss' ...
In answer to your last...yes and yes
 

bigasotonuk

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Hi,
Just to add to this thread.
As your car is a 1997 W202 C class, then it is entirely possible you have a single button flip out style fob rather than the three button electronic key which Malcolm was referring to in his earlier post, in which case unlocking the car with the key will sound the alarm but it will not silence till the alarm siren is turned off. If your key is indeed the single button type then the siren is IIRC on the passenger side just in front of the ABS Unit under the bonnet and is turned off via a key switch on the back of the siren with a separate small key.
Though on my 1997 C Class 230k I do not have a driver's door lock instead I have red/green LEDs and only a door lock on the front passenger door.
 
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Twinwasp

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Oh - my thanks again to all......

My remote is just one button and a metal key. There is a normal lock on the driver's door handle. The alarm shut off for mine is, I think inside the cabin on the driver's side just in front of the door, half way down the panel - it's a small black keyhole and I have a separate strange looking (presumably electronic) key that I guess I put in there and turn. I have seen reference to that in the handbook, so I'd better revise the page I think. Sounds as though there were different versions around 1997 when I imagine they upgraded things.

Useful to have these things up the sleeve isn't it, in case the remote fails when the car is locked. Fortunately this time, it was unlocked......

I'm so grateful that you chaps are so knowledgeable and happy to pas it on to folk like me.
 

Johnyk

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Good day guys. I'm a new, old merc owner. I have a 1997 W202 C180 in South-Africa. I have a problem where the car was locked by remote, single button flip key, the remote fell and wouldn't work anymore. So I unlocked the car with the metal key, passenger door. The alarm sounded and the key in the ignition didn't turn it off. So I disconnected the battery. Now I have a silent alarm going on. Car wont start, green and red mirror lights flashing intermittently. I took out the alarm fuse, and now the car starts. I have a secondhand key fob, with my original metal key inserted, but the 2 clicks towards mirror and then turn ignition to position 2, doesn't work. Any other way to syncronize the new fob to the armed alarm? Many thanks In advance
 
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Twinwasp

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Having written my post as below, I now see that earlier posts for a similar fault on my car some years ago have appeared, but I will submit my post in case anything additional is in it, that may help you.

Greetgings! I own a 1997 W202 C250 turbodiesel which must have the same alarming system. I guess you have read the handbook, but in case you haven't this is the essence of what to do. There may well be other members far more knowledgeable than me who will make other suggestions of course.

From your comments about the red and green lights on the mirror flashing intermittently, the handbook says there is a fault and you need to visit a garage. However, it may be that the fob batteries need changing. They are type 2025. Don't try to fit any other type. Don't handle the battieries with your fingers - use a lint-free cloth and fit them the correct way - the "+" symbol must be on the top for both batteries.

It may then be necessary to synchronise the lock system. With the fob with the replaced batteries, aim the fob at the mirror and press the button twice, briefly. Then put the key into the ignition and turn to position 2 (ignition on...). That should reset the system.

When the alarm sounded in your car, you need to put the key into the ignition switch and turning it onto position 2 (ignition on). If that does not work, use the small black key into the plug socket. That maybe in the glove compartment, or it may be the same place as mine, which is on the interior panel just in front of the driver's door, about half way down. Mine is right hand drive car and I guess yours is, being a South African car. If yours is left hand drive, the small plug socket would be on the left hand (driver's) door, or perhaps in the glove compartment as mentioned above.

If none of this works, then it will need a visit to your garage, or possibly a Mercedes garage I think.

Good luck........
Because the batteries had failed...
Be careful to use decent branded batteries not the pound shop specials- those will cause problems
 

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