Auxiliary Water Pump
WARNING: This page is about a different car, the 2005 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.
Vehicles equipped with a 3.9L engine are equipped with an auxiliary water pump. The auxiliary water pump is electrically driven and provides increased coolant flow during low engine speed operation. The pump is also used to circulate coolant after the engine is turned off under certain conditions.