FYI - For w210 owners with "silent" alarm
 

Just sharing part and fix info.....
Sitch: 99 E300. Lights flash and interior dome comes on when pushing the panic button on keyfob or when "violating" a door when alarm is set. However there is no squeal from the siren - all quiet.

Possible cause: I've heard these sirens actually have a battery on them that can corrode.

My fix: Part number 219 820 32 26 was installed today and all is working well.

ADDED BONUS: This new siren has a very unobtrusive beep when locking/unlocking now that matches signal light flashes.... i.e. 3 discreet beeps for locking and 1 for unlocking.

Hope this might be helpful for fellow w210 lovers.

Thanks for posting!

Wait, it's SUPPOSED to beep?!?! It sure is annoying that it doesn't!