You will be able to see Datacrons from quite a distance as they emit a large glow around them and shoot a beam of light into the sky. If you are very close to a Datacron you will also be able to hear the sound from them.
Datacron Locations By Planet
Coruscant – 5 Datacrons
Yellow: Presence +2 (Unlocks Galactic History Entry #8)
Location: 2320, 10551
Head to the Old Market area. As you run up the platform to get to the second level turn to the left and head up the platform to the third level. You will a small deck with two parked ships. The Datacron is on this platform.
Green: Endurance +2 (Unlocks Galactic History Entry #4)
Location: -3625, 150
Head to the Silent Sun Cantina inside the Black Sun area of Coruscant. You will be able to see and hear this Datacron from there. Across from the entrance (if you look at the entrance to the cantina, it will be to your right) you will see a bulldozer near a bunch of crates. Go around to the backside of the crates and you can climb up them. Work your way up to the top and across the pipe to the walkway. Follow the walkway until you reach the broken pipes in the wall. Jump onto the pipe and work your way across to the next platform. Run down the walkway to the next pipe and do the same. You will have to jump from pipe-to-walkway several times before making it to the appropriate platform with your Datacron.
Orange: Cunning +2 (Unlocks Galactic History Entry #5)
Location: 1020, -3969
This Datacron is in the Justicar Area. It will be hard to see, but it is on a platform above the hallway you are in. On the left side against the wall jump up the crates. Once on top you will have run across the pipes to make it to the platform with the Datacron. This one can be a bit tricky…time your jumps appropriately.
Yellow Matrix Shard (Unlocks Galactic History Entry #6)
Location: 950, 4541
Head to The Works section of Coruscant. On the east side of the map head to coordinates 1177, 4419. From here you can jump up onto the pipes. You will have to run along the pipes, crossing almost the entire zone to reach the platform this Datacron is located at.
Red: Strength +2 (Unlocks Galactic History Entry #7)
Location: -3087, 3031
This Datacron is inside the ruins of the Jedi Temple. On the east side of the ruins you will see a leaning pillar. Run up the pillar to the second level. From there, turn to the left and jump up onto the ledge along the wall. Follow the ledge around to the left. You will reach a platform where you can drop down. There is a mini-boss you will have to get past, he is easy. Then you can drop down from onto the pillar remains to claim your Datacron.