02 diesel c/c shortbox, trying to wire my truck into truck camper. Figured out marker lights and now trying to set up wiring to charge battery while truck is running. Camper only has four wires, black, white, brown and green. Green is for the marker lights, no idea on brown, assume white ground and black is for 12 volt.

truch has the wiring harness plugged into factory wiring below fule tank. I again assume the red is the batttery wire that should be connected to the black on the camper but it does not seem to assist in charging or providing power.

Any assistance welcome. on the road from Yukon to Disneyland and currently in the dark in Oregon

While the truck and camper wires may have the same colors, I strongly suggest testing each lead (volt meter, test lamp) to map out what each one is . . . just to be sure. Obviously, it's nice to have the truck wiring color codes and camper color codes as a starting point, but it's still a good idea to verify them.

On the truck, you could also check the trailer connector at the hitch (assuming you have one). Those colors should match the camper wires by the fuel filler.