Halo: The Master Chief Collection - Halo 2 - Obsessed - Halo 2: Activate Terminal 13 on The Great Journey. This achievement is fairly easy to unlock.
On the mission The Great Journey, midway through the mission you will enter a room with a bunch of enemies that looks like a jail.
On the top floor head to the right side to where there is an energy shield blocking you from entering. Destroy the shield and enter the area where the terminal is located against the wall at the end.
Run over and interact with it and your achievement should pop! Enjoy!