Alarm problems on SLK 1998

[HJH1944]

Hi has anyone had the problem with the alarm on SLK 1998 when the battery goes flats and is recharged when refitted to the car the alarm will not switch off the siren keeps sounding . Can anyone help.PLEASE it's driving me mad
Thanks. HJH1944

[Sparky137]

I've had this problem with both a C180 and a CLK320. If its the same system as these, the alarm siren has an internal battery. It is kept charged from the cars electrical system but as with all rechargable batteries, they don't last forever and they tend to be reluctant to hold charge after about ten years use. Problems with them can often be triggered by a poor car battery and once the problems start they will not stop. The answer is to replace the alarm siren module. They don't cost a fortune (the one for my CLK was £60 and it took about an hour to change).