Every time I start her up the exclamation .mark light and message about the security system come on. The red indicator on center of dash still blinks normal (every few seconds), doors lock, but haven't tested the siren by tripping alarm to see if it works. Is this almost always the nodule gone bad and if so any help on replacing would be appreciated 2005 S60T
Thanks

 

on some models the security system has a secondary battery. Wondering if that is what needs to be replaced?

 

It could be that the siren has failed.