Car Alarms: Car Alarm sounder, code alarm, somwhere

Question
I have a merc SL year 2000 which I assume at time of original purchase had an after market unknown approved alarm fitted.  There is an LED which pushes in and also a hidden electical key point.  I have had the car for a year and the siren vaguely sounded once(strangled sound)but never again only flashing indicators.  I have tried a combination of pressing the LED and inserting the electrical key which at one point stopped the flashing indicators but never sounded the alarm. I know the battery had run down this was replaced prior to taking delivery of the car???? Note I have another vehicle with a sigma alarm that has been standing for 2 years this also now only flashes the indicators??? Does this mean there is a seperate battery somwhere for the sirens??

Answer
The system sounds like a Code Alarm (the valet/LED switch pushes in and out)
But I am unfamiliar with the working of those units.

Try MY forum at www.INSTALLSUPPORT.com
for more on this fro my moderator Robert.

Also use the search bar there and type in Code Alarm
to see what comes back from past entries.

Good hunting.

ALARMTEK