2000 Nissan Xterra Alarm

I'm assuming that you're looking for the door trigger wire instead of the domelight supervision wire. On vehicles without power door locks use RED / black at any door switch or also found in the driver A pillar. Vehicles with power door locks use GREEN/ red for the driver door, GREEN/ black for the front passenger door, and RED / black for the rear doors. All found at the smart entrance control unit, use all three and diode isolate each. Smart Entrance Control Unit is above the hood release in the drivers kick panel. So I'm guessing you have power locks since you have the domelight time out feature. Use the three individual door triggers, it will provide you a good signal to the alarm regardless of whether the domelight is on or not. Life moves pretty fast; if you don't stop and look around once in a while; you could miss it.