adding a siren to factory alarm?

Did you get a Normally Closed, or a Normally Open switch? 

hmmm, not sure. i just saw one on ebay from a seller i previously purchased things from but the listing doesnt say anything about open or closed switch.

If you get it and it has only the 2 wires and no other connections, it is a Normally open switch.  Normally open as in in away from the magnet it will have no continuity between the 2 wires.  When the magnet comes close to the switch it will then allow current to flow. 

You will have to position it so that when the door is locked, the magnet is near the switch.  Do yourself a favor and mount the switch so it is stationary.  Mount the magnet to the moving part.  You will have to get the wires out of the door and into the cabin.  Use the 2 wires to interrupt power or ground on the scanner.

yea it only has 2 wires onthe one side. so will i need a relay in this too as far as it locking the doors when i drive and hit 15 mph? i dont need it to be scanning while driving and get pulledover.

I thought you already had the relay. You only need the one. Just use the 2 wires of the switch to make the circuit when the door is locked. Don't you have it working anytime the key is in the off position? if so, leave it like that and extend the 2 wires to the cabin, ground one of the wires, and ground the scanner to the other wire.

yea its still on a relay now. i wasnt sure if id have to rearrange the wires different on the relay to make all this work. so the only wire ill need to change is the ground wire of the scanner(which is grounded to chasis) to one end of the switch?

Correct. Ground one of the switch wires, and connect the ground wire from the scanner to the other wire of the switch.

heyi just wanted to give a big thank you for all the input on the scanner/mag switch wiring. works great as fro following your directions. only hard part was finding what to mount the non wire side of the switch to....ended up putting it on the actual door lck post(right below/underneath the door molding shell). only way i could do it was use a few zip ties to wrap around it and secure it snug as i could not gain access to any other parts. next ill try and tackle the horn/siren issue again in the next week or two. i also have those little uits from DEI that wind up windows with arm and i could vent/put them down with my old alarm. any way on getting tose in there somehow? atleast to wind up windows when pressing arm on remote...not concerned with the venting/putting down, if can be done great. im thinking no because i dont have an aux channel on the factory remote key fob. if its do-able with the factory alarm, might also get one for the sunroof since i have a bad habit of leaving it open on occassion. thx in advance.

anyone on my last post about the window modules?

and i connected everything up as directed. i can get it to do what its supposed to do....it chirps once on arm but does nothing on disarm. any suggestions?