the door trigger is not for arming the vehicle it is used for a trigger to set your alarm off
after locking the doors let it set for 60 sec. or so and see if it arms if not on some vehicle a secound pulse to the lock wire will arm it
I dont think you can rearm the Impala that way. Really the only way to know if you can though is to lock the doors with the aftermarket transmitter with the door open. If it arms then you should be able to do it. If not, then you can't. I doubt you can since none of my notes mention it as a possibility, and they usually do mention if that is how the vehicle works.
If your test shows that it can re-arm with the door open, then either you dont have a strong enough pulse, or you have the wrong wire. ............... OK as I was looking for what color you should be using for this to work, I saw a diagram for connecting an aftermarket alarm door trigger and there is a not mentioning how the drivers door pin wire can be used for rearming. It looks like you should be able to use the dark Blue wire which is the drivers door pin. It is in the same harness as your ORANGE / Black lock/Unlock wire and the Green disarm wire. If splitting your lock wire doesnt work, make sure you are splitting the wire before the 465 Ohm resistor. If it still doesnt work, try using a relay.
What unit did you install? Does it have a rearming wire?
-------------
J Rilla
Owner/Installer