I also own a 2001 325 which has an alarm that is "prewired" but not activated. Good news is that the "keyless" entry will work just fine. The center button locks the car. The key closest to the end where a lanyard would be attached opens the trunk, and the front button unlocks the driver door if pressed once, the passenger door when pressed again, and if held down, will open all the windows and sun roof as long as you hold the button in. It's slow, so you need to be patient, but they will open.