Fitment: 2004-2016 For Toyota For 4Runner 4.0L 2007-2014 For Toyota For FJ Cruiser 4.0L 2005-2009 For Toyota For Tacoma 4.0L 2010-2015 2004-2006 For Toyota For Tundra 4.0L Functions of the Thermostat: The thermostat is a critical component in a vehicle's cooling system, responsible for regulating coolant flow path to ensure the engine reaches and maintains its optimal operating Fast Warm-Up During a cold start, the thermostat remains closed, forcing coolant to circulate only within the engine to speed up warming. Temperature Regulation .
