FixerUpper

2013 Ford Edge, Driver side door was the culprit. Tried the lubrication method which didn't work. But I fixed it in 20 minutes. Remove the bottom door paneling to expose the wiring at the front. Use a tester that's earthed. You'll see a medium sized green wire. Earth that out and look to see if the Door Ajar warning goes off. If so, just run a wire from there to earth it out. Easy. However, remember that this now means you have no warning when a door is ajar, so that's a liability you have to take on yourself.