It is a feature of your aftermarket alarm system. I can enable and disable this feature on mine, you should be able to do the same. On my control module under the dash, there are some dipswitches that enable and disable all the features of my alarm. Most i have seen are the same way. So if you know where the main control module is, see if it has any switches and play w/ them to see what each one will control, or just consult the book for your alarm.