Open tail gate and look at end of cable it shoud be a large torx bolt remove bolt and bottom bolt should push down to larger opening. take off cable and replace new one. if you need other side done do that the same way
Firsy lower the tailgate to make this repair .If you do this one side at a time you will not need to find some thing to rest the tail gate on while you do the other side .After that remove the Hexhead bolts from the tailgate .Put the new cable on