taillight ???

i recently chopped the rear off the jeep, when doing so i had to cut thrue the wiring harness that powers the passenger side taillight, i figured id just splice into the drivers side to get brake and tail lights to work on the pass side again, well no go, i put the tester in the side that still works and it lights up i found the brake wire, and the tail light wire but when i attach them to the passenger side the passenger side, doesnt light up, is one of the wires a ground, is there a relay, ??? thanks///Kevin

No relay or fuse. Ill look at my harness when I get home, but everything for the pass side lights ran up the drivers D pillar. Is the harness still in the D pillar? Both sides run off of seperate wires. Look in your roof for the harness you cut in half, and use that.