I have the stock alarm and I took a look at the wiring connections for the horns inside the grill opening--it would be very easy for a thief to just unplug the horns before they broke into the car thus silencing the alarm (would take 15 seconds--the wires at the horn connections are right out in the open)
I'd like to add a siren to my stock alarm and not use the horn-----anyone done this? Is their a particular siren that would work well? would I need to use a relay? how does the wiring connect? (I notice the orange wire coming off the security module connects into the factory keyless door lock control unit circuit and uses the original horn relay to power the horn. Any help or advice would be much appreciated!!!

 

My 02 has two horns, on in the grill area and another under the hood forward of the battery - is this not the same as the 05?

You could just get any 12V Alarm siren and tap into the horn wiring under the hood. Of course your siren will go off whenever you honk the horn.

 

on mine, both my horns are out in front of the radiator which makes it easy to reach in and pull off the wires. If I added a siren to the existing horn wiring and installed it behind the radiator somewhere, that would work (and easy to do)---would I need to worry about the horn relay having enough "power"? or does a siren draw minimal current?
thanks for your input!

 

I think it would be OK, but you may want to use a relay just to be safe as I am not really sure what the siren would draw.