2010 GMC YUKON HYBRID service

Service
Doing Your Own Service Work
{WARNING:
Never try to do your own service on hybrid
components. You can be injured and the vehicle
can be damaged if you try to do your own service
work. Service and repair of these hybrid
components should only be performed by a
trained service technician with the proper
knowledge and tools.
{WARNING:
You can be injured and the vehicle could be
damaged if you try to do service work on a vehicle
without knowing enough about it.
.Be sure you have sufficient knowledge,
experience, the proper replacement parts,
and tools before attempting any vehicle
maintenance task.
.Be sure to use the proper nuts, bolts, and
other fasteners. English and metric fasteners
can be easily confused. If the wrong fasteners
are used, parts can later break or fall off. You
could be hurt.
6-2

If doing some of your own service work, use the proper
service manual. It tells you much more about how to
service the vehicle than this manual can. To order the
proper service manual, see“Service Publications
Ordering Information” in the owner manual.
This vehicle has an airbag system. Before attempting
to do your own service work, see “Servicing Your
Airbag‐Equipped Vehicle” in the owner manual.
Keep a record with all parts receipts and list the
mileage and the date of any service work performed.
See “Maintenance Record” in the owner manual.Checking Things Under
the Hood
High Voltage Devices and Wiring
{WARNING:
Exposure to high voltage can cause shock, burns,
and even death. The high voltage systems in your
vehicle can only be serviced by technicians with
special training.
High voltage devices are identified by labels.
Do not remove, open, take apart, or modify these
devices. High voltage cable or wiring has orange
covering. Do not probe, tamper with, cut, or
modify high voltage cable or wiring.
6-3

A. See“Engine Air Cleaner/Filter” in the owner
manual.
B. Drive Motor/Generator Control Module (DMCM). See Drive Motor/Generator Control Module
(DMCM) Cooling System on page 6‑9.
C. Engine Oil Dipstick. See “Engine Oil”in the owner
manual.
D. Automatic Transmission Fluid Dipstick. See Automatic Transmission Fluid on page 6‑5.
E. Brake Fluid Reservoir. See Brakes on page 6‑13.
F. See “Underhood Fuse Block” in the owner manual.
G. See “Windshield Washer Fluid” in the owner
manual.
H. Hybrid Auxiliary Fuse Block. See Underhood Fuse
Block on page 6‑26.
I. DMCM Coolant Surge Tank Pressure Cap. See Drive Motor/Generator Control Module (DMCM)
Coolant Surge Tank Pressure Cap on page 6‑8.
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
When to Check and Change Automatic
Transmission Fluid
It is usually not necessary to check the transmission
fluid level. The only reason for fluid loss is a
transmission leak or overheating the transmission.
If you suspect a small leak, then use the following
checking procedures to check the fluid level. However,
if there is a large leak, then it may be necessary to have
the vehicle towed to a dealer/retailer service department
and have it repaired before driving the vehicle further.
Notice: Use of the incorrect automatic transmission
fluid may damage the vehicle, and the damages may
not be covered by the vehicle's warranty. Always
use the automatic transmission fluid listed in
Recommended Fluids and Lubricants on page 7‑2.
Change the fluid and filter at the intervals listed in the
Maintenance Schedule. See Scheduled Maintenance in
the owner manual. Be sure to use the transmission fluid
listed in Recommended Fluids and Lubricants
on
page 7‑2.
6-5

The Drive Motor/Generator Control Module (DMCM)
coolant surge tank pressure cap must be fully installed
on the hybrid coolant surge tank.
Notice:If the pressure cap is not tightly installed,
coolant loss and possible damage to the Drive
Motor/Generator Control Module (DMCM) may occur.
Be sure the cap is properly and tightly secured.
Drive Motor/Generator Control
Module (DMCM) Cooling System
In addition to the regular cooling system, the vehicle
also has a cooling system for the DMCM system.
This system is serviced differently than the vehicle's
main cooling system. The DMCM cooling system
includes the DMCM coolant surge tank, DMCM surge
tank pressure cap, DMCM cooling pumps, hybrid
cooling radiator and the Drive Motor/Generator Control
Module (DMCM). The DMCM cooling system uses a
50/50 pre-mixed DEX-COOL™ coolant and deionized
water available at your dealer/retailer. See “Engine
Coolant” and“Cooling System” in the owner manual for
more information. When you decide it is safe to lift the hood, here is what
you will see:
A. Drive Motor/Generator
Control Module (DMCM)
B. Engine Coolant Surge Tank Pressure Cap
C. DMCM Coolant Surge Tank/Engine Coolant
Surge Tank D. DMCM Cooling
Hoses (Out of View)
E. DMCM Coolant Tank Pressure Cap
6-9

{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.
Notice: Using coolant other than a pre‐mixed
DEX-COOL, available at your dealer/retailer, 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.
6-11

Turn the DMCM coolant surge tank pressure cap
slowly counterclockwise (left) about one full turn.
Wait 30 seconds.
2. Then keep turning the DMCM coolant surge tankpressure cap slowly, and remove it.
3. Add the pre‐mixed DEX‐COOL™, available at your dealer/retailer, 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. 5. Add the pre‐mixed DEX‐COOL™, available at your
dealer/retailer, 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, your vehicle may need service. See your
dealer/retailer.
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.
6-12

Notice:
.Using the wrong fluid 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 fluid.
.If brake fluid is spilled on the vehicle's
painted surfaces, the paint finish can be
damaged. Be careful not to spill brake fluid
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.
{WARNING:
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.
6-15

Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly tighten wheel nuts in
the proper sequence to torque specifications in
“Capacities and Specifications”in the owner manual.
Brake linings should always be replaced as complete
axle sets.
Brake Pedal Travel
See your dealer/retailer if the brake pedal does not
return to normal height, or if there is a rapid increase in
pedal travel. This could be a sign that brake service
might be required.
Brake Adjustment
Every time the brakes are applied, the disc brakes
adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together if
the vehicle is to have really good braking. The vehicle
was designed and tested with top-quality brake parts. When parts of the braking system are replaced
—for
example, when the brake linings wear down and new
ones are installed —be sure to get new approved
replacement parts. If this is not done, the brakes might
not work properly. For example, if someone puts in
brake linings that are wrong for the vehicle, the balance
between the front and rear brakes can change —for the
worse. The braking performance expected can change
in many other ways if the wrong replacement brake
parts are installed.
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.
6-16