E class alarm, indicators flash rapidly

[Bill_H]

Hi - just looking for a quick bit of advice.
W210 E240 petrol year 2000, has been pretty much perfect for 10 yrs and 100k miles, (except for the rust that is).
Just developed a fault that I think is in the alarm system, when locking with the key fob, the indicators flash 3 times as normal but then continue to flash rapidly.
Have checked all door switches and boot switch all seem clean and working OK.
Also it now comes to mind that the alarm used to 'chirp' three times with the indicators when setting - and the chirp stopped about 3 months ago.

Is this the alarm system ?
If so I saw a few posts on here pointing at the siren module - is this a likely suspect? - If so where is it?

 

[Dec]

Have you tried triggering the alarm to see if it actually works? can’t help with the location of the siren on your car.

Dec

 

[bigasotonuk]

Hi,
Your siren is located under the front wheel arch liner on the passenger side of the car.
It is very likely that this is your issue, and they are about £70 you will need a T30 bit (security type) to remove it from the car and is just plug and play.
Before buying a new one it might be worth just closing "all" your heater vents, and disabling the motion sensors and the anti-jacking sensor, and see if that solves your problem first.

 

[Alex Crow]

good advice above - do try deliberately triggering the alarm to see if the siren does sound (as suggested). also beware, sometimes siren faults are actually wiring faults to the siren...

 

[Bill_H]

thanks for the advice, I haven't had a look yet as Im allergic to working under the car in cold weather! So have been locking with the mechanical key - which sometimes seems to trigger the alarm

Had a look at the pneumatic pump under rear seat and there was no apparent problem there, all nice and dry.
If the siren is a likely fault it probably explains the other symptom, that when the alarm is triggered (by me unlocking door with key), the siren sounds very sick in a croaky sort of way.
Is there any way of testing it ? Is it just a matter of unplugging it and seeing if the flashing indicator problem goes away?
Just to confirm - siren is on passenger side on a normal RH drive car. Is it easily recognisable once the wheel arch liner is off?

 

[television]

The croaky sound from the siren would indicate that it is at fault

 

[rpe2]

As above.

If the weather doesn't improve, there is a very good Independent' in your area who is a member on here -> http://forums.mercedesclub.org.uk/member.php?u=29766

 

[dieselman]

RApid flashing indicates the alarm has been triggered but after the initial siren and flashing have finished.
I think this may be either a dying alarm or car battery.