Page 34 of 98

Black plate (4,1)Chevrolet Tahoe and GMC Yukon/Yukon Denali Hybrid - 2011
9-4 Driving and Operating
Engine Coolant Heater
The engine coolant heater can
provide easier starting and better
fuel economy during engine
warm-up in cold weather conditions
at or below−18°C (0°F). Vehicles
with an engine heater should be
plugged in at least four hours before
starting. An internal thermostat in
the plug-end of the cord may exist
which will prevent engine coolant
heater operation at temperatures
above −18°C (0°F).
Using the Engine Coolant
Heater
1. Turn off the engine.
2. Open the hood and unwrap the
electrical cord. The cord is
secured to a wiring harness
between the engine and the
Hybrid Auxiliary Underhood
Fuse Block with a clip. Carefully
remove the wire tie which
secures the electrical cord. Do
not cut the electrical cord. 3. Plug the cord into a normal,
grounded 110-volt AC outlet.
{WARNING
Plugging the cord into an
ungrounded outlet could cause an
electrical shock. Also, the wrong
kind of extension cord could
overheat and cause a fire. You
could be seriously injured. Plug
the cord into a properly grounded
three-prong 110-volt AC outlet.
If the cord will not reach, use a
heavy-duty three-prong extension
cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug and store the
cord as it was before to keep it
away from moving engine parts.
If you do not, it could be
damaged. The length of time the heater should
remain plugged in depends on
several factors. Ask a dealer in the
area where you will be parking the
vehicle for the best advice on this.
Shifting Into Park
{WARNING
It can be dangerous to get out of
the vehicle if the shift lever is not
fully in P (Park) with the parking
brake firmly set. The vehicle can
roll. If you have left the engine
running, the vehicle can move
suddenly. You or others could be
injured. To be sure the vehicle will
not move, even when you are on
fairly level ground, use the steps
that follow. With four-wheel drive,
if the transfer case is in
N (Neutral), the vehicle will be
free to roll, even if the shift lever
is in P (Park). So, be sure the
transfer case is in a drive
(Continued)
Page 58 of 98

Black plate (10,1)Chevrolet Tahoe and GMC Yukon/Yukon Denali Hybrid - 2011
10-10 Vehicle Care
If the coolant inside the DMCM
coolant surge tank is boiling, do not
do anything else until it cools down.
The coolant level should be at or
above the FULL COLD mark with
the vehicle parked on a level
surface. If it is not, there might be a
leak at the DMCM cooler core,
DMCM pressure cap, DMCM cooler
hoses, DMCM cooling pump or
somewhere else in the DMCM
cooling system.Notice:
Running the engine when
there is a leak in the hybrid
cooling system can cause the
hybrid cooling system to lose all
coolant and can damage the
system. Get any leak fixed before
you drive the vehicle or run the
engine.
How to Add Coolant to the
DMCM Coolant Surge Tank
If no problem has been found yet,
check to see if coolant is visible in
the DMCM coolant surge tank. If coolant is visible, add pre‐mixed
DEX-COOL coolant, available at
your dealer, at the DMCM coolant
surge tank, but be sure the DMCM
cooling system, including the DMCM
coolant surge tank pressure cap, is
cool before you do it. Use the
procedure following.
{WARNING
Steam and scalding liquids from a
hot cooling system can blow out
and burn you badly. They are
under pressure, and if you turn
the coolant surge tank pressure
cap
—even a little —they can
come out at high speed. Never
turn the cap when the cooling
system, including the coolant
surge tank pressure cap, is hot.
Wait for the cooling system and
coolant surge tank pressure cap
to cool if you ever have to turn
the pressure cap.
Page 59 of 98

Black plate (11,1)Chevrolet Tahoe and GMC Yukon/Yukon Denali Hybrid - 2011
Vehicle Care 10-11
Notice:Using coolant other than
a pre‐mixed DEX-COOL, available
at your dealer, may damage your
vehicle. Any repairs would not be
covered by your warranty. Always
use a pre‐mixed DEX-COOL
(silicate-free) coolant in your
vehicle.
{WARNING
You can be burned if you spill
coolant on hot engine parts.
Coolant contains ethylene glycol
and it will burn if the engine parts
are hot enough. Do not spill
coolant on a hot engine.
If the DMCM coolant is empty, the
vehicle must be serviced by your
dealer and a special fill procedure
must be followed.
Notice: Attempting to fill the
DMCM cooling surge tank
yourself when the fluid level is
empty can damage your vehicle.
Your vehicle must be serviced.
1. Park the vehicle on a level surface and turn the vehicle off.
Remove the DMCM coolant
surge tank pressure cap when
the DMCM cooling system,
including the DMCM coolant
surge tank pressure cap and
DMCM cooling hoses, are no
longer hot. Turn the DMCM
coolant surge tank pressure cap
slowly counterclockwise (left)
about one full turn. Wait
30 seconds.2. Then keep turning the DMCMcoolant surge tank pressure cap
slowly, and remove it.
3. Add the pre‐mixed DEX‐COOL, available at your dealer, to the
DMCM coolant surge tank until
the level reaches the FULL
COLD mark.
4. Turn the ignition to ON/RUN without starting the engine. The
hybrid cooling pumps will run
and any trapped air will purge to
the surge tank.
Page 60 of 98

Black plate (12,1)Chevrolet Tahoe and GMC Yukon/Yukon Denali Hybrid - 2011
10-12 Vehicle Care
5. Add the pre‐mixed DEX‐COOL,available at your dealer, until the
coolant level is maintained at the
FULL COLD mark. This should
take no longer than two minutes
of hybrid cooling pump
operation.
If the level cannot be kept at the
FULL COLD level, the vehicle
may need service. See your
dealer.
6. Then replace the DMCM coolant
surge tank pressure cap. Be
sure the pressure cap is
hand-tight and fully seated. Notice:
Using tap water, cooling
system sealers or conditioners in
an attempt to stop coolant leaks
can damage the DMCM and
engine cooling systems. Never
use tap water, cooling system
sealers or conditioners in your
cooling system.
Power Steering Fluid
The vehicle has electric power
steering and does not use power
steering fluid.
Battery
This vehicle has a standard 12‐volt
battery and a high voltage hybrid
battery.
Refer to the replacement number on
the original battery label when a
new standard 12‐volt battery is
needed. Only a trained service technician
with the proper knowledge and tools
should inspect, test, or replace the
hybrid battery. See your dealer if the
hybrid battery needs service. The
dealer has information on how to
recycle the hybrid battery. There
is also information available at
http://www.recyclemybattery.com.
If an airbag inflates or the vehicle
has been in a crash, the vehicle's
sensing system might command the
automatic hybrid battery disconnect
to open. See
Replacing Airbag
System Parts After a Crash on
page 3‑2 for more information.
{DANGER
Battery posts, terminals, and
related accessories contain lead
and lead compounds, chemicals
known to the State of California to
cause cancer and reproductive
harm. Wash hands after handling.