2009 GMC YUKON HYBRID brake

Antilock Brake System (ABS)
Warning Light
For vehicles with the
Antilock Brake System
(ABS), this light comes on
briefly when the engine
is in ON/RUN.
That is normal. If the light does not come on then, have
it fixed so it will be ready to warn if there is a problem.
If the ABS light stays on, turn the ignition off, if the light
comes on while driving, stop as soon as it is safely
possible and turn the ignition off. Then start the engine
again to reset the system. If the ABS light still stays
on, or comes on again while driving, the vehicle needs
service. If the regular brake system warning light is
not on, the vehicle still has brakes, but not antilock
brakes. If the regular brake system warning light is
also on, the vehicle does not have antilock brakes
and there is a problem with the regular brakes.
SeeBrake System Warning Light on page 3-6.
For vehicles with a Driver Information Center (DIC),
seeDIC Warnings and Messages on page 3-12for all
brake related DIC messages.
StabiliTrak®Indicator Light
For vehicles with
StabiliTrak, this warning
light comes on briefly when
the ignition is in ON/RUN.
If it does not, have the vehicle serviced by your
dealer/retailer. If the system is working normally the
indicator light goes off.
When this light flashes, the system is on.
If it stays on while driving, there may be a problem with
the StabiliTrak system and the vehicle may need
service. See the owner manual for more information.
3-7

SERVICE BATTERY CHARGING
SYSTEM
If the hybrid battery system faults or fails this message
will appear on the DIC. The engine auto stop feature
will be disabled and the battery/charging system light will
appear in the instrument panel cluster. See “Battery
Warning Light” in the owner manual Index.
Driving with this light on could drain your batteries.
Have the electrical system checked as soon as possible.
Pressing the select button or the trip odometer reset
stem on the instrument panel cluster will acknowledge
this message and clear it from the DIC display.
HOOD OPEN
If the hood is not fully closed or there is a problem
with the hood switch, this message will be displayed.
Close the hood to clear the message. If the HOOD
OPEN message continues to be displayed after
verifying the hood is closed, you should have the hood
switch serviced. Pressing the select button or the
trip odometer reset stem on the instrument panel cluster
will acknowledge this message and clear it from the
DIC display.
When this message is displayed, the auto stop
function will not operate. If the vehicle is in auto stop
mode when this message appears, the engine will
instantly start.
OIL PRESSURE LOW STOP ENGINE
If engine oil pressure is low, this message will be
displayed on the DIC. Stop the vehicle as soon as safely
possible and do not operate it until the cause of the
low oil pressure has been corrected. Check your oil level
as soon as possible and have your vehicle serviced.
See “Engine Oil” in the owner manual Index.
SERVICE BRAKE SYSTEM
This message will be displayed if there is a problem
with the brake system. You will still be able to brake, but
it will be noticeably more difficult. Pull off the road to a
safe location and have your vehicle towed to the nearest
dealer/retailer for service. See “Brakes,” “Brake System
Warning Light,” and “ABS Brake System Warning
Light” in the owner manual Index.
SERVICE HYBRID SYSTEM
If this message is displayed on the DIC, the vehicle may
continue to operate, but you need to have it serviced
as soon as possible.
SERVICE POWER STEERING
This message displays if a problem has been detected
with the electric power steering. Have your vehicle
serviced by your dealer/retailer immediately.
3-13

Maximum trailer weight is calculated assuming only the
driver is in the tow vehicle and it has all the required
trailering equipment. The weight of additional optional
equipment, passengers and cargo in the tow vehicle
must be subtracted from the maximum trailer weight.Use the following charts to determine how much the
vehicle can weigh, based upon the vehicle model
and options.
Vehicle Axle Ratio Maximum Trailer Weight GCWR*
2WD 6.0 L V8 3.08 6,200 lbs (2 812 kg) 12,000 lbs (5 443 kg)
4WD 6.0 L V8 3.08 6,000 lbs (2 722 kg) 12,000 lbs (5 443 kg)
*The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and
trailer including any passengers, cargo, equipment and conversions. The GCWR for the vehicle should not be
exceeded.
Trailer Brakes
If a trailer is being towed that has trailer brakes and
the trailer brakes are manually applied while driving
slower than 25 mph (40 km/h), the vehicle may go into
auto stop mode even if the brakes are not being
pressed. Using the trailer brake system manually can
make the hybrid vehicle perform as if the brake pedalin the vehicle is being pressed. The trailer brake
operation check will still work. If the trailer brakes are
manually applied for an extended period of time,
the SERVICE BRAKE SYSTEM DIC message comes
on. The message goes off after the trailer brakes
have been released. No other action is necessary.
For more information, see “Trailer Brakes” in the Index
of the vehicle’s owner manual.
4-3

Service............................................................5-2
Doing Your Own Service Work.........................5-2
Checking Things Under the Hood.....................5-3
High Voltage Devices and Wiring......................5-3
Engine Compartment Overview.........................5-4
Automatic Transmission Fluid...........................5-5
Drive Motor/Generator Control Module (DMCM)
Coolant Surge Tank Pressure Cap..................5-6
Drive Motor/Generator Control Module (DMCM)
Cooling System...........................................5-6
Power Steering Fluid.....................................5-11
Brakes........................................................5-11
Battery........................................................5-15
Jump Starting...............................................5-16
Bulb Replacement..........................................5-21
Taillamps, Turn Signal, Stoplamps and
Back-up Lamps.........................................5-21
Replacement Bulbs.......................................5-22Electrical System............................................5-22
Fuses and Circuit Breakers............................5-22
Underhood Fuse Block..................................5-22
Tires..............................................................5-24
Inflation - Tire Pressure.................................5-24
Tire Pressure Monitor Operation.....................5-25
Tire Inspection and Rotation...........................5-29
Tire Chains..................................................5-30
If a Tire Goes Flat........................................5-30
Tire Sealant and Compressor Kit
(Without Selector Switch)............................5-32
Tire Sealant and Compressor Kit
(With Selector Switch)................................5-42
Tire Sealant and Compressor Kit Storage.........5-50
Capacities and Specications..........................5-52
Section 5 Service and Appearance Care
5-1

A. See “Engine Air Cleaner/Filter” in the owner manual.
B. Drive Motor/Generator Control Module (DMCM).
SeeDrive Motor/Generator Control Module (DMCM)
Cooling System on page 5-6.
C. Engine Oil Dipstick. See “Engine Oil” in the owner
manual.
D. Automatic Transmission Fluid Dipstick. See
Automatic Transmission Fluid on page 5-5.
E. Brake Fluid Reservoir. SeeBrakes on page 5-11.
F. See “Underhood Fuse Block” in the owner manual.
G. See “Windshield Washer Fluid” in the owner
manual.
H. Hybrid Auxiliary Fuse Block. SeeUnderhood Fuse
Block on page 5-22.
I. DMCM Coolant Surge Tank Pressure Cap. See
Drive Motor/Generator Control Module (DMCM)
Coolant Surge Tank Pressure Cap on page 5-6.
J. See “Coolant Surge Tank Pressure Cap” in
the owner manual.
K. Engine Oil Fill Cap. See “Engine Oil” in the owner
manual.Automatic Transmission Fluid
For more information, see “Automatic Transmission
Fluid” in the owner manual Index.
Checking the Fluid Level
Your vehicle’s automatic transmission dipstick looks like
this. For more information on location, seeEngine
Compartment Overview on page 5-4.
5-5

Power Steering Fluid
The vehicle has electric power steering and does not
use power steering fluid.
Brakes
Brake Fluid
The brake master cylinder
reservoir is filled with
DOT-3 brake fluid. See
Engine Compartment
Overview on page 5-4
for the location of
the reservoir.
There are only two reasons why the brake fluid level in
the reservoir might go down:
•The brake fluid level goes down because of normal
brake lining wear. When new linings are installed,
the fluid level goes back up.
•A fluid leak in the brake hydraulic system can also
cause a low fluid level. Have the brake hydraulic
system fixed, since a leak means that sooner
or later the brakes will not work well.Do not top off the brake fluid. Adding fluid does not
correct a leak. If fluid is added when the linings
are worn, there will be too much fluid when new brake
linings are installed. Add or remove brake fluid, as
necessary, only when work is done on the brake
hydraulic system.
{CAUTION:
If too much brake fluid is added, it can spill on
the engine and burn, if the engine is hot enough.
You or others could be burned, and the vehicle
could be damaged. Add brake fluid only when
work is done on the brake hydraulic system.
See “Checking Brake Fluid” in this section.
When the brake fluid falls to a low level, the brake
warning light comes on. See “Brake System Warning
Light” in the owner manual.
Refer to the Maintenance Schedule to determine when
to check the brake fluid. See “Scheduled Maintenance”
in the owner manual.
5-11

Checking Brake Fluid
Check brake fluid by looking at the brake fluid reservoir.
SeeEngine Compartment Overview on page 5-4.
With the engine not running for at least one minute, the
maximum fluid level (A) is at the top of the reservoir
body. With the engine running, the fluid level should be
in the proper operating range (B) between the MIN
and MAX marks. If it is not, have the brake hydraulic
system checked to see if there is a leak.After work is done on the brake hydraulic system,
make sure the level, with the engine running, is in
the proper operating range (B) between the MIN and
MAX marks.
What to Add
Use only new DOT-3 brake fluid from a sealed
container. See “Recommended Fluids and Lubricants”
in the owner manual.
Always clean the brake fluid reservoir cap and the area
around the cap before removing it. This helps keep
dirt from entering the reservoir.
{CAUTION:
With the wrong kind of fluid in the brake hydraulic
system, the brakes might not work well. This could
cause a crash. Always use the proper brake fluid.
5-12

Notice:
Using the wrong uid can badly damage brake
hydraulic system parts. For example, just a
few drops of mineral-based oil, such as engine
oil, in the brake hydraulic system can damage
brake hydraulic system parts so badly that they
will have to be replaced. Do not let someone
put in the wrong kind of uid.
If brake uid is spilled on the vehicle’s painted
surfaces, the paint nish can be damaged.
Be careful not to spill brake uid on the
vehicle. If you do, wash it off immediately.
See “Washing Your Vehicle” in the owner
manual.
Brake Wear
This vehicle has disc brakes. Disc brake pads have
built-in wear indicators that make a high-pitched warning
sound when the brake pads are worn and new pads
are needed. The sound can come and go or be heard all
the time the vehicle is moving, except when applying
the brake pedal firmly.
{CAUTION:
The brake wear warning sound means that soon
the brakes will not work well. That could lead to an
accident. When the brake wear warning sound is
heard, have the vehicle serviced.
Notice:Continuing to drive with worn-out brake
pads could result in costly brake repair.
Some driving conditions or climates can cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
the brakes.
5-13