Ford 2008 Escape Hybrid Owner's Manual page 10

Introduction
Frequently asked questions
Question
What is the pumping sound I
hear when I unlock or enter the
vehicle, and the venting sound a
few minutes after shutting off my
vehicle?
What are the series of clicks
from the cargo area when I first
turn the key in the ignition?
Why does the engine always start
at key-on?
After I start my car in the
morning, why does it take a long
time before the engine shuts
down?
10
2008 Escape Hybrid (ehv)
Owners Guide (post-2002-fmt)
USA (fus)
Answer
This is the hydraulic portion of your
regenerative braking system
pressurizing and depressurizing. You
may also hear it occasionally after
pressing the brake pedal.
The high voltage battery is
electrically isolated from the rest of
the vehicle when the key is OFF.
When the key is turned ON, high
voltage contactors inside the battery
are closed to make the electricity
available to the motor/generator and
enable the vehicle to drive. The
clicks are the sound of these
contactors as they close and open
during start up and shut down.
Your engine is started at key-on
because the emission components
need to be warm in order to
minimize tailpipe emissions, and in
cooler climates for cabin heating and
windshield defrost performance.
There are several reasons the engine
stays on for an extended amount of
time when it is first started. One
common reason is to ensure that the
emissions components are warm
enough to minimize tailpipe
emissions. As the climate gets
cooler, this "engine-ON" time is
extended.