Back up lights.....again

You need to diagnose the problem if simply replacing parts doesn't do it. Start with tthe bulb sockets, check for power and ground at the sockets. It's possible that the ground is faulty and you'll have to trace the ground circuit for the fault. If you have ground but no power, you'll have to trace the circuit back to the power source. It's possible that theh problem is in a connector so check for loose or corroded connectors. You could narrow it down by checking for power at the switch. If the switch turns on when it should, the poiwer fault is between there and the bulb sockets. If there's no power to the switch, you'll have to trace that back to the source for a fault. You may find that the switch doesn't turn on for some reason too so check that. Good luck. If you can't find it, try an auto electric shop or a Ford specialist. Here's a directory link for you: https://repairpal.com/ford-repair-in-huntington-new-york