fuel GMC YUKON 2012 Service Manual

Black plate (67,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-67
Filling a Portable Fuel
Container
{WARNING
Never fill a portable fuel container
while it is in the vehicle. Static
electricity discharge from the
container can ignite the fuel
vapor. You can be badly burned
and the vehicle damaged if this
occurs. To help avoid injury to you
and others:
.Dispense fuel only into
approved containers.
.Do not fill a container while it
is inside a vehicle, in a
vehicle's trunk, pickup bed,
or on any surface other than
the ground.(Continued)
WARNING (Continued)
.Bring the fill nozzle in contact
with the inside of the fill
opening before operating the
nozzle. Contact should be
maintained until the filling is
complete.
.Do not smoke while
pumping fuel.
.Do not use a cellular phone
while pumping fuel.
Towing
General Towing
Information
Only use towing equipment that has
been designed for the vehicle.
Contact your dealer or trailering
dealer for assistance with preparing
the vehicle for towing a trailer.
See the following trailer towing
information in this section:
.For information on driving while
towing a trailer, see “Driving
Characteristics and
Towing Tips.”
.For maximum vehicle and trailer
weights, see “Trailer Towing.”
.For information on equipment to
tow a trailer, see “Towing
Equipment.”

Black plate (72,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-72 Driving and Operating
Trailer Towing
If the vehicle has a hybrid engine,
see the Hybrid supplement for more
information.
Do not tow a trailer during break‐in.
SeeNew Vehicle Break-In on
page 9‑21 for more information.
{WARNING
The driver can lose control when
pulling a trailer if the correct
equipment is not used or the
vehicle is not driven properly. For
example, if the trailer is too
heavy, the brakes may not work
well—or even at all. The driver
and passengers could be
seriously injured. The vehicle may
also be damaged; the resulting
repairs would not be covered by
the vehicle warranty. Pull a trailer
only if all the steps in this section
have been followed. Ask your
(Continued)
WARNING (Continued)
dealer for advice and information
about towing a trailer with the
vehicle.
Notice: Pulling a trailer
improperly can damage the
vehicle and result in costly
repairs not covered by the vehicle
warranty. To pull a trailer
correctly, follow the advice in this
section and see your dealer for
important information about
towing a trailer with the vehicle.
To identify the trailering capacity of
the vehicle, read the information in
“Weight of the Trailer” that appears
later in this section.
Trailering is different than just
driving the vehicle by itself.
Trailering means changes in
handling, acceleration, braking,
durability and fuel economy.
Successful, safe trailering takes
correct equipment, and it has to be
used properly. The following information has many
time-tested, important trailering tips
and safety rules. Many of these are
important for your safety and that of
your passengers. So please read
this section carefully before pulling a
trailer.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how the rig is used.
Speed, altitude, road grades,
outside temperature, and how much
the vehicle is used to pull a trailer
are all important. It can depend on
any special equipment on the
vehicle, and the amount of tongue
weight the vehicle can carry. See
“Weight of the Trailer Tongue”
later
in this section for more information.
Trailer weight rating (TWR) is
calculated assuming the tow vehicle
has only the driver but all required
trailering equipment. Weight of
additional optional equipment,
passengers, and cargo in the tow
vehicle must be subtracted from the
trailer weight rating.

Black plate (79,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-79
brake controller is installed, the
ITBC must be disconnected. Do not
power both ITBC and aftermarket
controllers to control the trailer
brakes at the same time.
Tow/Haul Mode
Pressing this button at the end of
the shift lever turns on and off the
tow/haul mode.
This indicator light on the instrument
panel cluster comes on when the
tow/haul mode is on.Tow/Haul is a feature that assists
when pulling a heavy trailer or a
large or heavy load. See
Tow/Haul
Mode on page 9‑36 for more
information.
Tow/Haul is designed to be most
effective when the vehicle and
trailer combined weight is at least
75 percent of the vehicle's Gross
Combined Weight Rating (GCWR).
See “Weight of the Trailer” earlier in
the section. Tow/Haul is most useful
under the following driving
conditions:
.When pulling a heavy trailer or a
large or heavy load through
rolling terrain.
.When pulling a heavy trailer or a
large or heavy load in stop and
go traffic.
.When pulling a heavy trailer or a
large or heavy load in busy
parking lots where improved low
speed control of the vehicle is
desired. Operating the vehicle in Tow/Haul
when lightly loaded or with no trailer
at all will not cause damage.
However, there is no benefit to the
selection of Tow/Haul when the
vehicle is unloaded. Such a
selection when unloaded may
result in unpleasant engine and
transmission driving characteristics
and reduced fuel economy. Tow/
Haul is recommended only when
pulling a heavy trailer or a large or
heavy load.
Integrated Trailer Brake
Control System
The vehicle may have an Integrated
Trailer Brake Control (ITBC) system
for electric trailer brakes.

Black plate (88,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-88 Driving and Operating
Front axle reserve capacity is the
difference between the front Gross
Axle Weight Rating (GAWR) and the
front axle weight of the vehicle with
full fuel and passengers. Basically, it
is the amount of weight that can be
added to the front axle before
reaching the front GAWR.
The front axle reserve capacity for
the vehicle can be found in the
lower right corner of the
Certification/Tire label, as shown.
United States
CanadaIn order to calculate the amount of
weight any front accessory, such as
a snow plow, is adding to the front
axle, use the following formula:
(W x (A + W.B.)) /W.B.= Weight the
accessory is adding to the
front axle.
Where:
W = Weight of added accessory
A = Distance that the accessory
is in front of the front axle
W.B. = Vehicle Wheelbase

Black plate (90,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-90 Driving and Operating
Total vehicle reserve capacity is the
difference between the GVWR and
the weight of the vehicle with full
fuel and passengers. It is the
amount of weight that can be added
to the vehicle before reaching
theGVWR. Keep in mind that
reserve capacity numbers are
intended as a guide when selecting
the amount of equipment or cargo
the vehicle can carry. If you are
unsure of the vehicle's front, rear,
or total weight, go to a weigh station
and weigh the vehicle. Your dealer
can also help you with this.The total vehicle reserve capacity
for the vehicle can be found in the
lower right corner of the
Certification/Tire label as shown
previously.
See your dealer for additional
advice and information about using
a snow plow on the vehicle. Also,
see
Vehicle Load Limits on
page 9‑16.Emergency Roof Lamp
Provisions
Vehicles with the RPO VYU snow
plow prep package also have an
emergency roof lamp provision
package, RPO TRW. Wiring for the
emergency roof lamp is provided
above the overhead console. See
Auxiliary Roof-Mounted Lamp on
page 6‑7 for switch location.

Black plate (8,1)GMC Yukon/Yukon XL Owner Manual - 2012
10-8 Vehicle Care
Engine Oil
To ensure proper engine
performance and long life, careful
attention must be paid to engine oil.
Following these simple, but
important steps will help protect
your investment:
.Always use engine oil approved
to the proper specification and of
the proper viscosity grade. See
“Selecting the Right Engine Oil”
in this section.
.Check the engine oil level
regularly and maintain the
proper oil level. See“Checking
Engine Oil” and“When to Add
Engine Oil” in this section.
.Change the engine oil at the
appropriate time. See Engine Oil
Life System on page 10‑10.
.Always dispose of engine oil
properly. See “What to Do with
Used Oil” in this section.
Checking Engine Oil
It is a good idea to check the engine
oil level at each fuel fill. In order to
get an accurate reading, the vehicle
must be on level ground. The
engine oil dipstick handle is a yellow
loop. See Engine Compartment
Overview on page 10‑6 for the
location of the engine oil dipstick.
Obtaining an accurate oil level
reading is essential:
1. If the engine has been running recently, turn off the engine and
allow several minutes for the oil
to drain back into the oil pan.
Checking the oil level too soon
after engine shutoff will not
provide an accurate oil level
reading.
2. Pull out the dipstick and clean it with a paper towel or cloth,
then push it back in all the way.
Remove it again, keeping the tip
down, and check the level.
When to Add Engine Oil
If the oil is below the cross-hatched
area at the tip of the dipstick, add
1 L (1 qt) of the recommended oil
and then recheck the level. See
“Selecting the Right Engine Oil” in
this section for an explanation of
what kind of oil to use. For engine
oil crankcase capacity, see
Capacities and Specifications on
page 12‑2.
Notice: Do not add too much
oil. Oil levels above or below
the acceptable operating range
shown on the dipstick are harmful
to the engine. If you find that
you have an oil level above the
operating range, i.e., the engine

Black plate (12,1)GMC Yukon/Yukon XL Owner Manual - 2012
10-12 Vehicle Care
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 overheated
transmission. If a small leak is
suspected, 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 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 warranty. Always use
the automatic transmission fluid
listed in Recommended Fluids
and Lubricants on page 11‑11. Change the fluid and filter at the
scheduled maintenance intervals
listed in
Maintenance Schedule on
page 11‑3. Be sure to use the
transmission fluid listed in
Recommended Fluids and
Lubricants on page 11‑11.
How to Check Automatic
Transmission Fluid
Notice: Too much or too
little fluid can damage the
transmission. Too much can
mean that some of the fluid could
come out and fall on hot engine
parts or exhaust system parts,
starting a fire. Too little fluid
could cause the transmission
to overheat. Be sure to get an
accurate reading if checking the
transmission fluid. Before checking the fluid level,
prepare the vehicle as follows:
1. Start the engine and park the
vehicle on a level surface. Keep
the engine running.
2. Apply the parking brake and place the shift lever in P (Park).
3. With your foot on the brake pedal, move the shift lever
through each gear range,
pausing for about three seconds
in each range. Then, move the
shift lever back to P (Park).
4. Allow the engine to idle (500 –800 rpm) for at least
1 minute. Slowly release the
brake pedal.
5. Keep the engine running and press the Trip/Fuel button or
trip odometer reset stem until
TRANS TEMP (Transmission
Temperature) displays on the
Driver Information Center (DIC).

Black plate (23,1)GMC Yukon/Yukon XL Owner Manual - 2012
Vehicle Care 10-23
.Idles for long periods in traffic.
.Tows a trailer. SeeTrailer
Towing on page 9‑72.
If the overheat warning is displayed
with no sign of steam:
1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and to the highest
fan speed. Open the windows as
necessary.
3. In heavy traffic, let the engine idle in N (Neutral) while stopped.
If it is safe to do so, pull off the
road, shift to P (Park) or
N (Neutral) and let the
engine idle.
If the temperature overheat gauge
is no longer in the overheat zone
or an overheat warning no longer
displays, the vehicle can be driven.
Continue to drive the vehicle slowly
for about 10 minutes. Keep a safe
vehicle distance from the vehicle in
front. If the warning does not come
back on, continue to drive normally. If the warning continues, pull
over, stop, and park the vehicle
right away.
If there is no sign of steam, idle
the engine for three minutes
while parked. If the warning is still
displayed, turn off the engine until it
cools down. Also, see
“Overheated
Engine Protection Operating Mode”
later in this section.
Overheated Engine
Protection
Operating Mode
If an overheated engine condition
exists and the ENGINE POWER IS
REDUCED message is displayed,
an overheat protection mode which
alternates firing groups of cylinders
helps prevent engine damage. In
this mode, a loss in power and
engine performance will be noticed.
This operating mode allows the
vehicle to be driven to a safe place
in an emergency. Driving extended distances and/or towing a trailer in
the overheat protection mode
should be avoided.
Notice:
After driving in the
overheated engine protection
operating mode, to avoid engine
damage, allow the engine to cool
before attempting any repair.
The engine oil will be severely
degraded. Repair the cause of
coolant loss, change the oil and
reset the oil life system. See
Engine Oil on page 10‑8.
Engine Fan
If the vehicle has a clutched engine
cooling fan, when the clutch is
engaged, the fan spins faster to
provide more air to cool the engine.
In most everyday driving conditions,
the fan is spinning slower and the
clutch is not fully engaged.
This improves fuel economy and
reduces fan noise. Under heavy
vehicle loading, trailer towing, and/
or high outside temperatures, the
fan speed increases as the clutch

Black plate (35,1)GMC Yukon/Yukon XL Owner Manual - 2012
Vehicle Care 10-35
Headlamp Aiming
The vehicle has a visual optical
headlamp aiming system. The aim
of the headlamps has been preset
at the factory and should need no
further adjustment.
However, if the vehicle is damaged
in a crash, the aim of the headlamps
may be affected and adjustment
may be necessary.
If oncoming vehicles flash their high
beams at you, this may mean the
vertical aim of the headlamps needs
to be adjusted.
It is recommended that the vehicle
be taken to the dealer for service if
the headlamps need to be adjusted.
It is possible, however, to re-aim the
headlamps as described.The vehicle should:.Be placed so the headlamps
are 7.6 m (25 ft) from a
light‐colored wall.
.Have all four tires on a level
surface which is level all the way
to the wall.
.Be placed so it is perpendicular
to the wall.
.Not have any snow, ice, or mud
on it.
.Be fully assembled and all other
work stopped while headlamp
aiming is being performed.
.Be loaded with a full tank of fuel
and one person or 75 kg
(160 lbs) sitting on the
driver seat.
.Have the tires properly inflated.
.Have the spare tire in its proper
location in the vehicle.Headlamp aiming is done with the
vehicle's low-beam headlamps. The
high-beam headlamps will be
correctly aimed if the low-beam
headlamps are aimed properly.
To adjust the vertical aim:
1. Open the hood. See
Hood on
page 10‑52. Locate the aim dot on the lens of the low‐beam headlamp.
3. Record the distance from the ground to the aim dot on the
low‐beam headlamp.

Black plate (43,1)GMC Yukon/Yukon XL Owner Manual - 2012
Vehicle Care 10-43
The vehicle may not be equipped
with all of the fuses, relays, and
features shown.Fuses Usage
1 Right Trailer
Stop/Turn Lamp
2 Electronic Stability
Suspension Control,
Automatic Level
Control Exhaust
3 Left Trailer
Stop/Turn Lamp
4 Engine Controls
5 Engine Control
Module, Throttle
Control
6 Trailer Brake
Controller
7 Front Washer
8 Oxygen Sensors
9 Antilock Brakes
System 2 Fuses
Usage
10 Trailer Back-up
Lamps
11 Driver Side
Low-Beam Headlamp
12 Engine Control
Module (Battery)
13 Fuel Injectors, Ignition
Coils (Right Side)
14 Transmission Control
Module (Battery)
15 Vehicle Back-up
Lamps
16 Passenger Side
Low-Beam Headlamp
17 Air Conditioning
Compressor
18 Oxygen Sensors
19 Transmission Controls
(Ignition)
20 Fuel Pump Fuses
Usage
21 Fuel System Control
Module
22 Headlamp Washer
23 Rear Windshield
Washer
24 Fuel Injectors, Ignition
Coils (Left Side)
25 Trailer Parking Lamps
26 Driver Side Parking
Lamps
27 Passenger Side
Parking Lamps
28 Fog Lamps
29 Horn
30 Passenger Side
High-Beam Headlamp
31 Daytime Running
Lamps (DRL)
(If Equipped)
32 Driver Side
High-Beam Headlamp