The lights should work any time you try them.... if you are not plugged in then they will run off the battery. I have the same model...mine work anytime I try them.
Most likely you have a loose wire somewhere, maybe a loose wire nut or wire clamp connector. They sometimes use those pinch together connectors that you squeeze with pliers.
I just now went out and did some fuse pulling and here is what I found. The kitchen light, range hood, and the front lights are all on the same circuit. On mine, it is the 4th fuse from the top. So.... if you kitchen light works, then check the range hood light. If it works, then you may have a loose wire inside the range hood... pull it apart and check. If the range hood also fails to work, remove the kitchen light and check the connections there.
The lights are very easy to remove and since it is a 12 Volt system, you will not get shocked.
2008 - 189 FBR
2007 Jeep WK Limited CRD