Hey guys 2015 here. Didn't see anybody post the fix so I am. Where the wire harness pass into the body on the right hand side the wires rub on an un-grommeted hole, the insulation comes off and they short.
Open the tailgate, locate rubber wire tube on right side. Pull off lower connection, see busted wires. Isolate and wrap them in electrical tape. Armor bundle against rubbing.