Noise when unlocking or locking car

[connashio1]

Hi all,

This is hard to explain if you don't hear the noise I do. When I unlock or lock my car (53 plate W211) there is a high pitched electronic tone that is coming from within the engine bay. The noise is loud enough to be heard from within the car but is muffled once I close the door. It seems to be on the drivers side but I cannot pin it down. There are no error messages on the dash when this is happening. Re-locking or unlocking the car makes no difference. After 5 minutes or so it just stops. The alarm would be the logical suspect but it doesn't seem loud enough.
Any ideas or has anybody had the same issue themselves?

All help greatly appreicated, Paul

 

[whitenemesis]

On a 53 plate car the alarm siren module could be on the way out, the batteries corrode and die.

Does the alarm go off if you open the locked driver's door using the emergency blade?

 

[connashio1]

On a 53 plate car the alarm siren module could be on the way out, the batteries corrode and die.

Does the alarm go off if you open the locked driver's door using the emergency blade?

I'll give that a try and will report back.

Thanks, Paul

 

[connashio1]

I'll give that a try and will report back.

Thanks, Paul

OK....if I unlock the car with the fob or the key blade all is OK. If I lock the car with the key blade all is OK. If I lock the car using the fob the alarm sounds for six and a half minutes. It does seem the alarm is faulty. If I buy a new one will the car need any STAR diags done afterwards? From searching it seems the unit itself is around £90 and fitting is a DIY job.

 

[connashio1]

Well, that really was easy. New siren fitted in less than an hour, no problems at all. Alarm is now working perfectly. Thanks to everyone for the info.....

Cheers, Paul