[JRTJH]

What Chuck is saying is that once you get the 12 volt positive (black wire in the umbilical cable) and the ground (white wire in the umbilical cable) identified and connected (look at which trailer wire goes to the battery positive terminal (12 VDC Positive) and which wire goes to a screw on the chassis (ground) and have them connected to the trailer wires in the junction box, then you can use that 12 volt power to "jumper to every other wire in the trailer junction box. Use a small wire connected to the "known 12 volt positive" and as you touch each wire in the junction box, identify which bulbs on the trailer illuminate. Then, connect that wire to the umbilical wire per the color code in the etrailer link that Chuck provided. As you connect each wire, move to the next and do the same. Once they are all connected, then plug the trailer umbilical into the truck and make sure the lights work with the truck power.

You'll need the trailer battery cutoff switch in the connected position to feed the trailer 12 volt power to the junction box for this procedure to work. If the BCO switch is disconnected, you won't have 12 volts on the junction box and this process won't work.....

Sounds complicated, but is really easy to do once you figure out which bulbs are lighting when you power each trailer wire in the junction box... Use the etrailer link to determine which color wire in the umbilical cord to connect to each trailer wire in the junction box.....