NikleinR6

So the newest issue my car has been having, is that when i lock the doors with the smartkey, about 20 secs later my alarm sounds for no reason, and then the tow away lights begin flashing. At 1st i thought, maybe the rear battery is going, then i thought maybe water was getting into my trunk and shorting the pse pump, and lastly i thought maybe my rear SAM was going bad. Luckily for me, it happens that the siren (mounted beneath the driver's side fender) contains its own 2 batteries, and these go bad. When they go bad, they leak battery acid all over the board, corroding it, and leaving you with these issues : everytime the alarm is activated, the siren will sound soon thereafter. The car thinks its being towed/stolen...

Its easy to fix, just remove left front wheel, the rear part of the inner fender liner, and then reach inside (under the fender) and remove the siren. I decided to remove it with the bracket (3bolts as it seemed the easiest). You can buy a replacement from parts.com for 103.00. I left mine out until i decide if i really want to spend 120.00 shipped on something that is useless. I can always order it, and install it in under 20min if i want to later.

I found many other MB owners have the same problem as i think the siren is the same for the entire mb line of cars (pertinent years).
I have a bunch of pics i thought you guys might wanna see that show the damage.. I sawed the siren in half, just to take a look...

gtchow

Thanks for the info. My 04 SL55 AMG had the siren go off while driving :-)
I also cut open the siren and one of the battery was leaking and it possibly shorted the circuit board somewhere and the siren will come on with no warning.
Originally I was going to clean out the circuit board, replace the 2 batteries and use some epoxy to glue it back. It will be much cheaper than spending the $200 bucks for the replacement siren. But then you can never be sure that the circuit board will not short again.
Just went to a MB dealer and got the replacement part. The siren went through several revisions since 2004 and the present one is slightly smaller and without the female thread hole, instead it has a male thread protruding out, so you need a metric nut to secure it to the box under the wheel well. I suspect there might not be any batteries in the new model since it is smaller. What a horrible design to have batteries inside the siren!

mkhurley

So your saying this doesn't need to be there?? It'll start stop and show no errors if this isn't there??

I'll add an image to this to help folks understand where and what it looks like in the fender. Just removed mine. What he shows above is inside the sheetmetal cover.

damian155

I had the same problem a couple months ago and also changed it myself .. didn't take long.. simple job.
parts.com
The updated replacement part adds a beep to the lock and unlock modes.

0-60inAMG

Just wanted to thank you for the pictures and the guidance, completed the job yesterday and all went great.

Adarah

this is a great thread - thank you so much for the info and pictures!

I am having the same issue with my clk 320, its at the dealership now and i am considering bringing it home and attempting to do it myself...

jagata

Bringing back a old thread. Does anyone have the part number to the updated siren, I would like the added chirp when arming and disarming.

4thSL

Had to have mine replaced last year when it starting going off in a hotel parking lot while on a road trip. Paperwork lists part number as 219-820-32-26. It has the chirp.

harryv

Thanks for forwarding this thread. The local MB dealership told me they think it's the SAM; I certainly believe this is the problem. I will remove the alarm siren first. I'll add a post at a later date to let you know if it worked.
Thanks, HarryV

GrepAwk

Especially while you are repairing or inspecting you ABC lines in the same vicinity!

clarifications:

- yes, there is still a NiMH battery inside of the replacement siren. It's there as a backup in the event a thief steals/disables your main battery.

- dealers charge $200-$220 for the replacement. Online dealers charge $150. Other online part sources charge $100.

- The bolt head on the original siren was the Torx security bit style. That will slow you down. Get a variety pack of bits that includes this style, or drill a small hole in the end of your Torx driver to make one. As mentioned by previous poster, the replacement sirens include a threaded stud for which you are going to need a washer and nut. I recommend a NylaLock nut so it doesn't rattle off.

2003sl55AMGCN

I had a similar problem with my 2003 SL55 AMG - the alarm would go off for no reason as soon as the car was locked. Turned out to be a faulty key fob. Ordered a replacement from the MB dealer in Calgary for about $425 which came pre-programmed.

moggieme

Having read a number of threads tackling this issue of the alarm siren on all MB models, I am still in a bit of a quandry over a similar issue with my 1999 320 CLK Convertible, with the hazard lights flashing continuously after locking. However, when I press the 'Lock' button on the key a number of times, the siren will still sound. Does this just mean that the siren will still need replacing, as the internal batteries are still holding some charge, or does it point to another problem, say, with the SAM?