How to change thermostat 2005 GMC Envoy?

To change the thermostat on a 2005 GMC Envoy, first ensure the engine is cool and disconnect the negative battery cable. Drain the coolant from the radiator, then remove the upper radiator hose connected to the thermostat housing. Unbolt the thermostat housing, replace the old thermostat with a new one (making sure to align it correctly), and reassemble everything by reversing the steps. Finally, refill the coolant and check for leaks.