In chapter 9 You'll find a tram and get it running, well when you(Isaac clarke),Ellie,And stross get on and start going it will say "Malfunction something is blocking the way" so You have to get out of the tram and go remove it, BEFORE YOU START GOING ON WITH THE OBJECTIVE WHEN YOU GET OFF THE TRAM you'll see breakable boxes by the tram, collect what is in there and look over the railing on both sides, There should be a schematic thats blinking in the dark over the railing use kinesis to pick it up and put it in your inventory. By the way! you have to Complete the game Once on any difficulty to see it!