Cabin Heater Coolant Pump

The cabin heater coolant pump is utilized to circulate coolant though the vehicles cooling system based on certain vehicle demands. During low engine speeds the pump increases heater core flow that the main engine coolant pump provides. The specific RPM threshold varies based on the ambient and coolant temperatures. It also supplies coolant flow during an auto start - stop condition to maintain the cabin temperature when the cabin heat is turned on. The pump also turns on in response to high engine oil temperatures and increases the flow through the oil cooler to reduce the oil temperature. The pump is commanded on by the PCM.