viper 771xv, 2005 envoy

Well I am not exactly sure what the dome input wire is connected to because I removed this from my old Envoy and installed it on my new Envoy. I only hooked up wires that were hooked up before. Now that I think about it though I did not hook up a couple wires that I thought were not needed like the dome supervision output(because the 445g already provides dome supervision through the data wire, and the parkinglight wire because the lights already come on when I remote start and I don't care if the flash when I lock or unlock but it does flash upon unlock anyways.  I don't think I ever had my alarm go off from the doors being opened before and I do remember the installer saying something about needing to diode isolate the door triggers but i thought the 455g kept you from needing to diode isolate.

Couldn't I hook the door triger into the horn? Because when I open the door the factory alarm goes off and the horn honks.