Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.
1-18 Description and Operation
Engine Control Components
Typical Cold Start Valve
Cooling Fan
The PCM monitors certain parameters (such as engine coolant temperature, vehicle speed, A/C ON/OFF status, A/C pressure) to determine engine cooling fan needs.
For Variable Speed Electric Fans:
The PCM controls the fan speed and operation using a duty cycle output on the FCV circuit. The fan controller (located at or integral to the engine cooling fan assembly) receives the FCV command and operates the cooling fan at the speed requested (by varying the power applied to the fan motor).
The fan controller is able to detect certain failure modes within the fan motors. Under certain failure modes, such as a motor that is drawing excessive current, the fan controller shuts the fans off. Fan motor concerns may not set a specific DTC. With the fan motor disconnected from the fan controller, voltage may not be present at the fan controller.
For Relay Controlled Fans:
The PCM controls the fan operation through the fan control LFC (single speed applications), and LFC (low speed), MFC (medium speed), HFC (high speed) for multiple speed applications. Some applications have the xFC circuit wired to 2 separate relays.
For 2 speed fans, although the PCM output circuits are called LFC and HFC, cooling fan speed is controlled by a combination of these outputs.
For 3 speed fans, although the PCM output circuits are called LFC, MFC, and HFC, cooling fan speed is controlled by a combination of these outputs.
Cooling Fan Clutch
The cooling fan clutch is an electrically actuated viscous clutch that consists of 3 main elements:
• a working chamber
• a reservoir chamber
• a cooling fan clutch actuator valve and a fan speed sensor (FSS)
The cooling fan clutch actuator valve controls the fluid flow from the reservoir into the working chamber. Once viscous fluid is in the working chamber, shearing of the fluid results in fan rotation. The cooling fan clutch actuator valve is activated with a pulse width modulated (PWM) output signal from the PCM. By opening and closing the fluid port valve, the PCM can control the cooling fan speed. The cooling fan speed is measured by a Hall effect sensor and monitored by the PCM during closed loop operation.
The PCM optimizes fan speed based on engine coolant temperature, engine oil temperature, transmission fluid temperature, intake air temperature, or air conditioning requirements. When an increased demand for fan speed is requested for vehicle cooling, the PCM monitors the fan speed through the Hall effect sensor. If a fan speed increase is required, the PCM outputs the PWM signal to the fluid port, providing the required fan speed increase.
2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.