Alarm and key query

[MarkJunedd]

In the last two days I have had this strange thing happen and want to know if its normal or not.
Sunday unlocked car,opened passenger door to put 18mth old grandaughter in her seat, while buckling her in, alarm went off.
Yesterday unlocked car, opened passenger door to let my good lady in, walked into garage to get something, as I returned, alarm went off.
I know that if you dont open the drivers door after a certain time after unlocking that it will re-lock so is there a similar thing going on with the alarm maybe?
Also I only have one electronic key, any body know the cost of a spare while i'm sitting down?

 

[bennesspipers]

You ought to tell us where you are,& what the car is, like give us a clue.

 

[MarkJunedd]

How stupid of me I thought you all could guess! Its a 98 CLK 320

 

[bennesspipers]

It could be that the batteries in your key fob are getting low,so 1st option (& quite cheap) is change them.
Regards your key,is yours the old style one button with flip out key ? If it is they are about £180, think the later ones are just over £200. DONT buy one off e-bay, they CANNOT be reprogrammed, whatever the seller says !
Good luck.

 

[MarkJunedd]

I should been clearer sorry, mime is the three button electronic key with the mechanical blade in the side which does not flip out. So the battery is a changeable affair is it? Hate to ask but in the event that the battery should fail, would I be unable to start the car?

 

[Dec]

As far as I know the battery is needed only for the central locking but not positive about that, you could remove the batteries from the fob to see if the car will start without them.
See… YouTube - LLave Mercedes Clase C (W203)

Dec

 

[m7m]

Yes. When the battery in my key ran out, I opened the door with the mechanical key and had no problem starting the car.

 

[MarkJunedd]

I'll get some new batterys and give it a whirl but cant see that making a difference to the alarm going off to be honest.

 

[Dec]

When you unlock a car you also disarm the alarm, clearly your alarm isn’t being disarmed OR it is rearming itself.

It could be a faulty siren or dieing/leaking rechargeable batteries inside? the siren, it would be worth locating and examining the siren and its connections .

Dec

 

[BlackC55]

Very likely to be a faulty siren.

 

[MarkJunedd]

Thanks for the input, its strange that the alarm isnt disarming although i'm not sure if its the same caper as the locks wherein it checks for the drivers door opening within 30 secs of unlocking or else it relocks. Its more of an annoyance than anything.

 

[Dec]

It shouldn’t be doing all that, it may be an intermittent fault now but could become chronic in the future.

When the alarm is triggered in the way you describe, do the hazards also flash at the same time? Try purposely triggering the alarm so as to compare a genuine alarm incident with this faulty alarm incident.

The alarm siren is the main suspect as it usually is located in quite a harsh environment.


Dec