Inoperative license plate light

Our license plate light didn't work at pick-up, but it was getting dark and threatening  mega rain. We would look at it later, how hard could it be? We had not planned on driving after dark so it could wait for another day. That other day had arrived.

What we found was that the lead from the camper, going toward the license light,  had power and it was the correct polarity. Red was positive and white was negative (white negative is standard in 12 V systems). The problem, we found, was that the jumper that plugs into that lead had reversed colored wires. Evidently the electrician hooking up the license plate light assumed it was correct and spliced white to white and black to red. Oops...doesn't work n this case. Evidently LED lights are polarity sensitive and don't work in reverse polarity mode. (Evidently quality control didn't get a complete check mark that day).

Our solution: New butt splices from the license plate light to the jumper. We cut both wires from the light, above the splices, and reconnected. We hooked from the light, white to red, and black to white. (Remember our jumper had reversed color coding). Voila...We have light.