I'm not sure I follow what you are trying to do... IS there 3 trucks? how are they set up? what are you trying to rob from one to make the other work? be a little more clear about what you are trying to do/accomplish... Please...

I don't have the oem wiring pics here at work... You'll need the wiring diagrams for all 3? trucks so you can match the wires... Or you'll have to power the wires with 12v current to find the back up light wire. Or if someone else on here understands what is going on better than I and have the right diagrams????