Cabin Heater Coolant Pump
WARNING: This page is about a different car, the 2016 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The cabin heater coolant pump is available on 2.7L EcoBoost ® vehicles equipped with the auto start-stop feature only. The PCM sends a PWM signal to the cabin heater coolant pump. The cabin heater coolant pump provides coolant to the heater core whenever the HVAC system requests heat and the vehicle is in auto start-stop mode. Refer to the Owner's Literature, Unique Driving Characteristics, for full auto start-stop enabling/disabling information.