compatibillity issue

Leave it in the corner. The factory alarm does not have the input capability for add on sensors.Top Secret, I can tell you but then my wife will kill me.

well......you can, but it won't function properly as a 2-stage motion sensor. you can have it as a single stage sensor with the inner zone connected to your door or hood trigger. but that means it will have to be on all the time. power drain is very little. just make sure to diode isolate with door or hood trigger. just make sure nothing is moving in the vincinity of your vehicle when you arm it or the factory alarm will "see" that a door (or hood) is open. if you really insist on having the outer zone working, that can be done too but it's very annoying. install some form of switch to manually turn on the motion sensor, and then have the outer zone trigger a beeper or small siren. but that means that you'll hear it sounding everytime you switch it on (because of course the switch will need to be somewhere in the car) when you exit. personally, i'd go with Forbidden's suggestion. good luck! all problems can be resolved with a hammer

Which is why I didn't dwell into what you did. It can create a nightmare for a new installer. Good info, I should have said yes it can be done but it is an involved installation that is best done by someone familiar with alarms and diodes.Top Secret, I can tell you but then my wife will kill me.