Outback Model

Disconnect the ground cable from battery.
Remove the rear gate upper trim.
1. Release the claws in the trim end.
2. Disconnect the claws in the center of trim, and remove the rear gate upper trim.
  
  Fig 1: Removing Rear Gate Upper Trim
  Courtesy of SUBARU OF AMERICA, INC.
Remove the high-mounted stop light.
1. Remove the nuts and take out the high-mounted stop light toward vehicle rear.
  
  Fig 2: Locating High-Mounted Stop Light Nuts
  Courtesy of SUBARU OF AMERICA, INC.
2. Disconnect the connector and remove the high-mounted stop light.
  
  Fig 3: Disconnecting High-Mounted Stop Light Connector
  Courtesy of SUBARU OF AMERICA, INC.