Car Alarms: blinkers flashes when door is open (disarmed), nissan 240sx, negative pulse

Question
i hooked up the door trigger wire to the dome light wire. the blinker flashes when door is opened for both armed and disarmed situations. even if it is flashing it still let me start the engine but won't let me take out the keys until i close the door. malfunction? wrong wire?  (nissan 240sx 1990)
and also i have some trouble hooking up the central lock system for sigle wire. manual doesn't have the diagram for single wire door lock system.
thx!

Answer
I do not think I have enough information to fully answer this question but I will try with this.  There are some vehicles that use an electro-mechanical interlock that will not allow you to remove the key from the ignition in certain situations, typically though it references the position of the gear shifter not the door.  This sounds to me as if you may be on the incorrect wire and when the door is open it is feeding back into that circuit.

To your door locking system, here is what DEI lists on your car:

This is one of the three known systems Nissan used in early production. To operate, open(cut) the org/blk wire and the doors will lock, pulse the same wire to ground and the doors unlock. The other two systems are negative pulse (orange/black for lock and orange/blue for unlock both at the door lock timer in the passenger kick behind the ecm.) and non-centralized - add actuator in drivers door.

So, the easiest way to check to see if it in deed the one wire system just cut the wire in question and if your doors lock then it is the one wire if they do not it is one of the other 2 types.  The negative trigger is the easiest with the non-centralized being the most time consuming to interface with.  If you find that your system is a one wire that requires a ground pulse and separating the wire then wire your relay like what is shown in this diagram:

http://www.the12volt.com/doorlocks/page2.asp#n1

Hope this helps