Inside the Ford Fusion hybrid

Jan. 1, 2020
Let's be honest, the original Honda Insight was an ugly car. In fact, most of the early hybrid offerings were ugly cars, at least in my humble opinion.

Up close and personal with the Ford Fusion hybrid

undercar Ford Fusion hybrid repair shop training technician training A/C training automotive aftermarket Let's be honest, the original Honda Insight was an ugly car. In fact, most of the early hybrid offerings were ugly cars, at least in my humble opinion. But then again, I grew up in the Muscle Car era with the Boss Mustang, HEMI-powered Super Bees and the Bandit's Trans Am. Those were the days when fuel mileage wasn't an issue; horsepower and styling sold cars.

Today, there are nearly 40 different models of hybrid and battery electric (BEV) vehicles for sale in the United States. Hybrids make up the fastest growing segment of new car sales, driven not only by increasing consumer concerns over fuel costs but a real desire to reduce environmental impact and conserve natural resources. Hybrid owners, by and large, are as into their cars as the hot-rodders of days past and very likely know as much or more about the technology involved as their repair shops of choice do. They generally are affluent (upper middle income), able to afford the initial purchase and the expenses associated with the maintenance and repair of their pride and joy.

Ford's Hybrid History

Did you know that the most popular cars back in the first years of the automobile's existence by and far were electric? Those who could afford this new mode of transportation didn't like the smell and grime, or the work involved, in driving a gas-powered car. Back in 1913, Henry Ford and Thomas Edison actually collaborated on at least two totally electric vehicles. The Model T, however, was never offered as a BEV.

In the mid-1960s, Ford developed the Comuta, an experimental prototype that used four lead-acid batteries connected in series to provide its 48-volt power source. It had a top speed of 25 mph and a range of 40 miles. In 1979, Ford's electric car research program debuted a Ford Fiesta that used a nickel-zinc battery that yielded a 100-mile range with a top speed of 65 mph. Other noteworthy moments in Ford's hybrid history include the ETX-II (1988), the Connecta (1991), the Ecostar (1992) and the Ranger EV/Postal program (1998).

But the Ford hybrids you are most likely familiar with are also Ford's first production hybrid offerings, the Ford Escape hybrid and its cousin, the Mercury Mariner hybrid, released in 2004. Building on that experience, Ford introduced a hybrid version of its popular Fusion model in the 2010 model year, the same year the Fusion line was named Motor Trend's Car of the Year.

The Fusion hybrid is one of 14 Ford vehicles that offers best in class fuel economy with an EPA rating of 41 miles per gallon city and 36 miles per gallon highway. Its power comes from a combination of its 2.5-liter Atkinson cycle 4-cylinder internal combustion engine (ICE), producing a maximum of 156 hp and 136 foot-pounds of torque, and its permanent magnet AC electric motor-generators. The motors are fed by a nickel-metal hydride 275v battery pack and the traction motor is capable of producing 106 hp for a combined net rating of 191 hp. Power is fed via a planetary gearset similar to that used in other Ford hybrids to an electronically controlled continuously variable transmission (eCVT).

The Powertrain

The High Voltage Traction Battery (HVTB) assembly is located behind the rear seat and contains several components including the Battery Energy Control Module (BECM), Battery Pack Sensor Module (BPSM), cooling fan and related ductwork. The battery assembly, including the service disconnect plug, is accessed by first releasing the seat latch securing the passenger seat back. This latch is a little awkward to get to. It is located on the trunk side of the seat, and partially hidden in the space just above the cooling fan assembly. You must first remove the trunk trim and then look closely or you may miss it.

The HVTB consists of D-cell type batteries packaged into modules and supplying an operating range of 179-343 DC volts. It provides power to one of the two motor-generators contained in the eCVT, one designated the generator motor and the other the traction motor. The first provides cranking for the ICE and an HV AC power source when the engine is running that can recharge the battery pack or provide power to the traction motor for propulsion. The traction motor can operate in electric-only mode up to 47 miles per hour (the ICE will also shut down when coasting at or below 47 mph). Additionally, it is used to provide extra power under heavy load when the ICE is already running.

Common to hybrid battery failures is the imbalance between cells that occurs over time. To maintain peak efficiency, Ford uses a procedure called the R-Mode Rebalance. The rebalance process charges the battery to near a full state of charge and keeps each individual cell charge within a specified range of each other. The R-Mode Rebalance is controlled by the BECM and is sometimes run during vehicle operation. If the BECM cannot maintain the balance on its own, a DTC will set and the process checked/performed in the service bay with a scan tool.

Other HV components you'll find on the Fusion include the eCVT transmission, DC to DC converter and the Air Conditioning Control Module (ACCM) and compressor. The HV system uses a floating ground to completely isolate it from the vehicle chassis. The BECM monitors the system for any leakage of current to the low voltage system.

The Fusion's gasoline engine is a 2.5-liter, dual overhead cam four-cylinder with four valves per cylinder. Fuel is provided via a sequential multi-port injection system and lit by a standard coil-on-plug ignition system. Both the head and block are of aluminum construction.

The fuel injectors get their fuel from a two-speed mechanical returnless fuel system (MRFS). Filling the tank with gas is done through an Easy Fuel™ capless fill tube. In the event an impact is detected, the Restraints Control Module can send an event notification signal on a dedicated line to the Fuel Pump Control Module to shut down the fuel pump. Cycling the key off then on should reset the FPCM and allow restart. This is a separate feature from the HV Vehicle Shutdown that occurs whenever the battery is about to open the HV contactors (due to an internal fault detection or an external event).

Additional Notes

There are two cooling systems on the Fusion hybrid, one for the ICE and one for the HV electronics and transmission. The engine's cooling system uses an auxiliary electric coolant flow pump for passenger heat when the engine is not running and improved circulation at lower engine speeds. The HV system also uses an electric pump for coolant circulation, and both systems have their reservoirs under the hood for easy inspection. This is typical of many hybrid designs and stresses the need to review the service procedures you need to follow to properly maintain them. The HV battery system is air-cooled by a dedicated cooling fan and ductwork that draws in air from the passenger cabin from a grill located in the base of the rear passenger seat.

An HV A/C compressor handles passenger cooling. When the HVAC control module makes an A/C request, a message is sent from the module over the Medium Speed Controller Area Network (MS-CAN) bus to the Instrument Cluster (a gateway module). From there, it is delivered to the Powertrain Control Module (PCM) on the High Speed CAN line (HS-CAN). If all the conditions required by the PCM for A/C operation are met, it sends a control signal to the A/C Control Module and regulates cooling not by cycling the compressor on and off, but by varying compressor speed. A humidity sensor inside the cabin monitors relative humidity and can alter compressor speed accordingly to maintain passenger comfort while minimizing electrical load.

The Fusion hybrid also incorporates an electronic power steering system (EPAS). The Power Steering Control Module (PSCM) communicates over the HS-CAN and is attached to the right side of the EPAS assembly. It is not serviceable separately. The electric motor is a 12-volt reversible design connected to the steering rack by a toothed belt and a pulley/bearing assembly. Motor position is used to determine steering wheel angle/position instead of a separate sensor. A steering shaft torque sensor is used by the PSCM to determine how much force is being applied to the steering wheel. The sensor sends out two signals; one for left and one for right. The signal matching the direction of rotation increases while its opposite decreases, allowing the PSCM to determine the direction of steering input.

The Fusion hybrid instrument panel display features Ford's SmartGauge™ with EcoGuide, designed to coach drivers on optimizing their hybrid's performance. You might know this design by the highly publicized leaves that grow as your driving efficiency improves. Utilizing two high-resolution, full color LCD displays on either side of the analog speedometer, drivers can choose from one of four distinct lay-outs and a tutorial on the differing displays is available on initial key on.

Other features of the Fusion include SYNC®, allowing hands-free access to phone (Bluetooth® enabled) and digital media (through USB connection) and the SOS Post-Crash Alert System® that automatically flashes the signal lights and sounds the horn in the event of an accident.

Driving Impressions

Like many of you, I've been to the training sessions and I've even done some work on hybrids, but I've never lived with one. Ford was kind enough to loan me a Fusion for a few days in preparation for this story, so I had a chance to get a sense of what it meant to be a hybrid owner.
The Fusion is a roomy, mid-size sedan and the model I had was equipped with all the accoutrements you could want. There was plenty of power, and it was delivered seamlessly to the wheels. The only way I could tell how much of that accelerative G-force came from the ICE and/or the traction motor was from the display on the instrument panel's LCDs. In fact, the only way I could tell I was driving a hybrid was from the hybrid body tags and the green vine that was growing in the right hand corner of the IC. With fuel mileage figures rivaling my little Corolla, it was easy to consider making the Fusion a more permanent part of my life. I was doing my part for the environment and not sacrificing my creature comforts to do so!
Many say that hybrid costs do not yet outweigh their benefits, and with plenty of conventional offerings competitive in meeting the fuel mileage figures they offer, that may be true. But as I mentioned early in this article, most hybrid owners are hybrid owners for a different reason, a "higher calling" if you will. And that same passion for their car of choice makes them excellent customers for those that understand their views — and their cars.

Watch a video of Pete's test drive in the AutoPro Workshop by logging on to

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