Cabin Heater Coolant Pump
WARNING: This page is about a different car, the 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
Vehicles equipped with the 3.5L EcoBoost engine have the auto start-stop feature as standard equipment, which includes a 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. The PCM sends a PWM signal to control the cabin heater coolant pump. Refer to the Owner's Literature, Unique Driving Characteristics for full auto start-stop enabling/disabling information.