i have a 2000 expedition and the license plates are not working, i replaced the bulbs but i still have no lights. what could be the problem and or where can i get power from to make the lights work....thanks for the help

 

Without knowing anything else, my bet would be a bad ground. check the wiring coming out of the lamp sockets

 

I agree, probably a bad ground. The lights are single wire, they ground with contact to the bumper. The edges of the holes in the bumper or the contact area of the light fixture, or both could by rusty. Not allowing the ground contact needed. It's not uncommon to need to replace the back-up light fixture itself, as the series of tabs that hold it in deteriorate over time. Regardless it's usually an easy, one wire fix. New ones will either have a male bullet connector that will plug in, or simple splice it in with a weather proof connector.