Tag light out?

I have the same truck. It was a rebuilder, so I'm pretty familiar with the wiring. It was repaired by a friend with a body / repair shop where he specializes in rebuilding one and two-year-old Dodge trucks.

This diagram is for the exterior lighting, but it's too hard to read. First, try to copy and paste it into a typing program where it can be expanded. I use MS Word.

The second diagram is expanded to show the two fuses. They are okay because a lot more would be not working if one was blown. The third diagram is the expanded part showing the two license lamps. If one is working and one is not, suspect a corroded splice, SP2232, (blue arrow).

If both lights are dead, a good test point can be found in the inline body / chassis connector, pin 10. That one sits just behind the left front wheel, on the outside of the frame rail, in a very vulnerable location. Mine was damaged in the crash. The last drawing shows that connector view. The wire is white / light blue. A lot of the wires look the same at first so they're easy to mix up. On mine, the rear lighting wires are mostly white, and the orange, light brown, gray, and yellow tracers look similar. I ended up with a warning message, "left backup light out" when it's the right one with the broken wire. I mixed those wires up when repairing them.

If you're getting a warning message on the dash, suspect that white / light blue wire has a break in it. Check for voltage on both sides of that chassis connector by back-probing through the rubber weather seals around that wire. Let me know what you find.