I have a 1996 4Runner SR5 with a trailer plug (OE ?). When returning from a trip and turning off the ignition, the tail lights remained on. I tried turning the headlights on and off with no success. I resorted to disconnecting the negative battery cable to prevent the battery from draining, until I can come up with a better solution. Any suggestions about how this can be resolved in a more permanent way?

Update: I learned that at least one of the wires entering the rear gate from the top was severed and the insulation was missing on several of the others. This was found after removing the black protective sleeve attached to the body at one end and the gate on the other. The mechanic reconnected the severed wire and repaired the missing insulation. As a result, all seems to be working fine.