?? from a newbie

I have been playing & learning with textures & night lighting to get the a/c night lighting like I want it (cabin & tail lights on when landing lights aren't). I did this before successfully a number of times, but I don't remember how I did this;I can get the tail & cabin lights to turn on with the cockpit lighting, but the fuselage wash from the landing lights comes on too. How, or can I get the fuselage wash to come on with the landing lights and not with the cabin & tail lights?Rick