This Datacron unlocks the codex entry - Galactic History 81: The Battle of Telos Four
This datacron holds unheard of power and knowledge collected by an ancient race. You access its power and discover writings which are clearly only one small piece of a massive galactic history:
The forces of the Sith Triumvirate had hunted the Jedi almost to extinction. The Jedi Exile, cut off from the Force, went in search of the remaining Jedi Masters and, perhaps, an explanation. But the Exile's mentor, Kreia, had other plans--when the Exile finally gathered the Masters, Kreia slew them all.
As the Exile recovered from this encounter, Kreia deliberately enticed the terrible Darth Nihilus to the planet Telos Four. Nihilus prepared to devour all life on the planet, and Nihilus's dreadnought, the Ravager, was met by the Republic Navy and Mandalorian forces.
During the battle, the Exile boarded the Ravager and faced Nihilus. Unable to devour the Exile as he had so many others, Nihilus was finally defeated. With Telos safe, the Exile pursued Kreia.
To retrieve this Datacron you will want to go all the way northeast in Labor Valley to the Advanced Product Research Sector (Screenshots 1 & 2). Directly in front of me in (Screenshot 2) is the steel beam that you can jump from to the awning of a building. You will want to do this and follow that awning all the way south over top the roadway (few jumps here) and across the other awning to the south. This awning will wrap around the building until you come across some gray flex (Screenshot 3). (You may think it's a pipe, it kind of is, it's like a scrunchy pipe used in HVAC)
You will need to jump to this gray flex and follow it until you get to where I am in (Screenshot 4), it's only a few feet ahead. From here you will want to jump to the metal plate, which is closer or the shuttle thing if you're awesome and you think you can make it (I did the shuttle thing, cause I'm awesome). Follow this shuttle thing up a bit until you get 3/4 of the way up it. Off the right hand side you will see a large platform which is actually a covered road, you will need to jump down to this. Make sure you're mounted and jump down to this road.
Once you're here turn around and go back to the western most end of this broken road, right where I am in (Screenshot 5) and slowly back up down to the metal pipe with a blue "X" on it in the picture. After you fall down onto that pipe, jump into the broken road and run north to grab your Datacron prize.