Driving Your Hybrid Hybrid System; Typical Hybrid Sounds - GMC tahoe 2009 Getting To Know Manual

Getting to Know Your Tahoe/Yukon 2-Mode Hybrid
2
DRIVING YOUR HYBRID
Hybrid System
Your Tahoe or Yukon 2-Mode Hybrid
drives just like a regular vehicle, but it
has several fuel-saving features that
increase vehicle efficiency and maximize
fuel economy. The hybrid features of
your vehicle are enabled after the
engine warms up to proper operating
temperature.
Your 2-Mode Hybrid vehicle includes
electric motors housed in the electrically
variable hybrid transmission, a Vortec
V8 engine with Active Fuel Manage-
ment™ and a 300-volt Energy Storage
System. The V8 engine is not designed
for E85 fuel.
A sophisticated electronic control
module selects the most efficient mode
of operation based on the amount of
power demanded by the driver and
battery charge level.
In the first mode, under light accelera-
tion and at speeds between 20 and 30
mph, the vehicle may be powered by
only the electric motors, the engine,
or a combination of both.
The fuel-saving electric-only feature is
referred to as Auto Stop. It will turn off
the engine until the driver requests
increased power or the hybrid battery
needs charging.
The second mode is used primarily at
highway speeds and when trailering, in
conjunction with the engine's Active Fuel
Management, to optimize fuel economy
while providing power when conditions
demand it.
The hybrid battery stores power for use
when the vehicle's engine is off while in
Auto Stop mode and supplies power for
the various electric motors used in the
2-Mode Hybrid system. The hybrid
battery is recharged by the vehicle
during deceleration and while braking.
It does not need to be plugged into an
electrical outlet.

Typical Hybrid Sounds

Your hybrid vehicle has several electric
motors, including the motors in the
transmission that help power the vehicle
as well as the air conditioning compres-
sor, brake pump, coolant pumps and,
within the Hybrid Energy Storage
System, a cooling fan and electrical
contactor switches. At times, you may
hear these motors start up or stop, and
they might produce a slight whirring,
humming or blowing sound typical of
electric motors. These are normal
sounds found on a hybrid vehicle and
may be more noticeable when the vehi-
cle is operating in the Auto Stop mode
with the engine off.
Your hybrid vehicle also does not make
an audible starter noise when starting
the vehicle. Therefore, it may seem to
take slightly longer to start than a non-
hybrid vehicle. If the key is not held in
the start position long enough, the vehi-
cle will not start but the instrument panel
cluster warning lights will illuminate,
requiring the key to be turned to the
start position again. You may also expe-
rience a perceived hesitation when
selecting Reverse after starting the
vehicle.
See your Hybrid Owner Manual.