Omega Normally Closed Trigger Sensor For Ford Lincoln & Mercury VehiclesNormally Closed Door Trigger adapter converts normally closed trigger circuits to standard negative trigger outputs. Ideal for Ford, Lincoln, Mercury Vehicles 5 normally closed trigger inputs (ground = not triggered, nothing = triggered) 1 negative trigger output Connect to trailer wiring and detect trailer disconnect Loop the trigger input wire through assets like toolboxes. When the wire is broken, the alarm will trigger