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Escape/Mariner Hybrid SUV

The hybrid Escape and Mariner vehicles are full hybrid vehicles. Being a full hybrid means that, at times, the vehicle will run 100% on electric power only. In fact, it is capable of traveling up to 25mph (40kph) without ever starting the engine. At times, the engine may shut off at speeds as high as 40mph (64kph). Plus, when conditions are right, the engine may shut off at stops and not restart until after 25mph. As a result, the advertised fuel economy of a full hybrid vehicle is typically much higher for the city driving conditions than the highway driving conditions. In theory, assuming the person's trip was short enough, a person could drive in slow moving stop and go traffic without using any gasoline at all. How is all of this achieved? And what does it mean to the service technician?

Hybrid Operation Modes

The high voltage electric motor and 4 cylinder engine will trade off between each other while driving, as well as team up at times to propel the vehicle. The electric motor also plays an equally important role during braking and recharging the vehicle's batteries. The PCM decides when to trade one power source for the other and when to team them up.

Startup: When the key is first turned to the start position, the engine will start up. Since there is no conventional electric starter on the vehicle, this action is performed by the 330 volt electric motor located inside the transmission. There is no starter noise that is normally associated with an engine under cranking conditions. The only noise is the engine suddenly running. If the high voltage battery has a proper charge, and the climate control demands will allow it, the engine will shut off after a minute or two.

Electric Drive: The first movements from the vehicle, under light throttle, are silent as only the electric motor propels the vehicle along at slow speeds. It will remain in electric drive mode up to 25mph under light throttle as long as the HV batteries do not run low on charge or get too hot, or the climate control needs do not demand the engine to start.

Regenerative Braking: During the deceleration process, the traction motor becomes a voltage generator. This effectively slows the vehicle down in conjunction with the friction brake system. The traction motor is capable of generating up to 397 volts and 78 amps. The high voltage generated from the traction motor is sent to two different locations. One location is the high voltage batteries under the floor of the cargo area (see high voltage battery pic below),

and the other is the DC to DC converter located on the right inner fender (see DC to DC convert pic below).

The DC/DC converter replaces the need for a belt driven alternator. The DC/DC converter steps the high voltage down to 12 volts. During this voltage step down process, the output amperage is multiplied. The DC/DC converter is equal to a 110amp alternator. This serves to power the 12 volt electrical system and recharge the conventional lead/acid 12 volt battery under the hood. The ABS module calculates the amount of braking desired by the driver based on input from the accelerator pedal position sensor, the brake pedal pressure sensor on the master cylinder, and the longitudinal accelerometer. This information is shared with the PCM so that the PCM can control the transmission to generate voltage from the traction motor. Simply letting off of the gas pedal signals for some regenerative braking, applying the brake pedal signals for more.

Electrical Assisted Driving: Normally, at highway speed the gasoline engine is powering the vehicle. However, when more torque is needed (such as when passing), the electric motor will kick in and add it's torque to the driveline as well. As a result, the little 2.3L may now feel more like a 3.0L to the driver. At times, the electric motor may pull the high voltage batteries down to as low as 216 ...

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