I let my wife drive it this past Sun and when she came back, the door ajar had reared its head. I had suffered with a door ajar issue fairly infrequently, and always resolved it by shutting each door a second time and that usually fixed it. This time, it wasn't so easy. I read this particular thread and did some testing. Here is my process:
1 - Verify the door ajar light stays on after shutting each door (including lift gate) a second time.
2 - Check the power door locks on the drivers door. Test the power mirrors as well. If they work on the driver door, the driver door is not the issue (more than likely you will stop at this test because the drivers door is the issue).
3 - Run above test on the passenger door. If you can't operate the power lock, the ground is bad.
4 - To repair the ground, open the suspected door. Locate wire boot in hinge.
5 - Squeeze in the door side of the boot (part that goes into door) and lift gently toward front of vehicle. Be gentle or you will loose the ends of your broken ground.
6 - You may have to cut around the boot to get to the wiring, just be careful.
7 - Carefully look at the wiring to find the broken wire. Mine was completely cut in half. Perfectly shiny copper wire was exposed.
8 - Once you find that break, get some spare wire in the 4" long range. Strip the ends of your splice.
9 - It was easier for me to splice by grabbing the broken wire with a pair of needle-nose pliers and stripping the ends of the broken wire that way.
10 - Twist on your splice and tape or shrink tube it.
11 - Replace the boot and push it back into the door.
12 - Start the car and verify your power door locks and mirror work as well as the door ajar light being off.
13 - Go buy gasoline, because a door ajar light won't do squatt to get you home if you run out.