On my terzo the alarm when i try to set it just emits a tone and won't stop untill i unset it. it's a factory fitted cobra 6422 cat 1. any help would be appreciated as i don't like leaving it unalarmed. once in a blue moon it will set then justs goes off after a couple of hours.

 

Im pretty sure that the tone is a warning to tell you that something is left open. At a guess i would say that there is a problem with either the door, boot or bonnet switches.

 

thanks for the reply i'll have a look into the sensors although i dont know where they all are apart from the bonnet one and it seems fine.