Adding a pager and tilt sensor

The car will be mostly indoors, will sensitivity change because of the exterior temperature?

Any other proximity sensor that you would recommend?

Need to diode isolate the sensors, where can i get 1N4001/L diodes? Do i have to mention other specs while ordering like ampere rating etc.?

OEM BMW alarm made by Alpine with built in glass sensor, have Alpine added shock sensor, now i need to add a pager DEI 795T and tilt sensor DEI 507M. The alarm does not have a "ground when armed" wire, how can this be resolved, think need the relay but need more instructions -what model, how to do the wiring in order to make a "ground when armed" wire.

If you have a real electronics store locally you can get them cheap.... they should be around a dime apiece.... The net is not hardly worth it because of shipping unless you need other parts.

At the Shack they cost substantially more.  Radio Shack has them but I hate going in there.  I have more than once gone to a local Stereo/ Alarm shop.  And asked the installer for some.... the last time I bought 5 of them for a buck.

It is an OEM factory BMW alarm made by Alpine, i need to have a ground when armed wire every time i arm the alarm and no ground when disarming the alarm.  The alarm harness plu has 12 pin connector, 2 of those pins are door lock + and door unlock +. Would this be the easyest way to create ground when armed from these 2 pins using relays. I believe both lock and unlock wires have a one time pulse + current. How can i do this.