i have a 05, can i install a aftermarket motion detect alarm that will work along with the existing alarm? if not, can i wire in an alarm flashing dash light with the existing alarm?

 

you genraly dont want your stock alarm on with an after market alarm. mine was turned of through the modual for my new alarm i put in, with a series of buttons and key turning.

 

I also agree, you don't really want two separate systems running- you really want one system or the other. If you just want a blinking light on the dash, that's no biggie- you can just get a basic flashing LED module- hook up a relay to the ignition, and use the NC output of the relay (the center pin of a regular 5 pin auto relay). That way when you turn the car on, the ignition energizes the relay and closes the NO contact (opening the NC contact and shutting your LED off)- then when you shut the ignition off, the LED will start immediately.

Also, I'd think twice about a motion sensing alarm- what are you specifically worried about someone stealing? If you're worried about rims, they have level sensors that go off if the car is jacked too far off axis; if you're worried about contents- the combination of regular door sensors, a glass break sensor, and a shock sensor are more than enough to cover normal thieves.

I just hate doing the motion sensors because I've had too many complaints about false alarms (myself included). I used to have a DEI on on my monte, and I would get multiple false alarms a day. I realize you can adjust the size of the zones, but I never could get it dialed in where you could have it go off if someone stuck their arm in the window, and not have it pick up false alarms from other stuff outside the car.