A Secret in Song
The quest is unlocked after completing The Future of Hyrule scenario.
"You heard a rumor that a songstress with the Rito tribe knows a tune that tells of ancient technology, and possibly the parts you seek. Give the diva gems—she'll sing you that song."
"Clad in the gems you gave her, the songstress performed the tune, which did reveal a promising location. Upon visiting the spot, you found parts that might revive Terrako!"