T-SB-0051-12 - Driver’s Seat Popping/Creaking/Squeaking From Lumbar Area (March 1, 2012)
Some 2010 – 2011 4Runner vehicles may exhibit a condition where the driver’s side seat back lumbar area makes a pop, squeak, or creak noise while driving. The condition may become more evident when driving on rough or uneven road surfaces or while moving around in the seat, especially if the lumbar support is fully extended. Replace the front seat back spring assembly to address this condition.
popping/creaking noise on seats?
https://www.toyota-4runner.org/tsb/2...squeaking.html