You can find a description of the BIRD module operation in the forum's library in the Power and Electrical category. This is for a module with five wires. Some have four wires. The difference is that the five wire ones have an "Auxiliary" connection that comes from the emergency start switch and the four wire ones have the emergency start switch wired as a jumper to the isolation relay.
Forest River Forums - Downloads - Intellitec BIRD Datasheet 00-01000-000.pdf
I attached a photo of the area under the steering wheel to show the 5 amp inline fuse that feeds the "IGN" terminal on the BIRD on our Ford chassis. You can see the inline fuse holder with the blue wires. An orange wire goes under the door kickplate to the BIRD connector.
Also, do you know for sure that the isolation relay is working? As the Intellitec BIRD datasheet describes, when you are on shore power, it should connect the coach 12 volt system to the chassis 12 volt system to keep the chassis battery charged. You can verify it is doing that by checking the voltage on the chassis battery when on shore power. It should show about 13.5 volts if it is being charged, but about 12.5 volts if it is not being charged. If the BIRD is working properly you should have 12 volt power on the relay terminal with the red wire when the BIRD operation calls for the coach and chassis systems to be connected (coach charging chassis, chassis charging coach, or emergency start switch depressed).