Page 361 of 490

Black plate (23,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
Vehicle Care 10-23
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.
{Warning
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 on page 5-21.
Refer to the Maintenance Schedule
to determine when to check the
brake fluid. See Maintenance
Schedule on page 11-2.
Checking Brake Fluid
Check brake fluid by looking at the
brake fluid reservoir. See Engine
Compartment Overview on
page 10-5.
The fluid level should be above
MIN. 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 is above the MIN but not over
the MAX mark.
What to Add
Use only new DOT 3 brake fluid
from a sealed container. See
Recommended Fluids and
Lubricants on page 11-12.
Page 362 of 490

Black plate (24,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
10-24 Vehicle Care
Always clean the brake fluid
reservoir cap and the area around
the cap before removing it. This
helps keep dirt from entering the
reservoir.
{Warning
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.
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.
Battery
Refer to the replacement number on
the original battery label when a
new battery is needed. See Engine
Compartment Overview on
page 10-5 for battery location.
{Warning
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.
Vehicle Storage
{Warning
Batteries have acid that can burn
you and gas that can explode.
You can be badly hurt if you are
not careful. See Jump Starting on
page 10-76 for tips on working
around a battery without
getting hurt.
Infrequent Usage: Remove the
black, negative (−) cable from the
battery to keep the battery from
running down.
Extended Storage: Remove the
black, negative (−) cable from the
battery or use a battery trickle
charger.
Page 363 of 490

Black plate (25,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
Vehicle Care 10-25
Four-Wheel Drive
Transfer Case
When to Check Lubricant
Refer toMaintenance Schedule on
page 11-2 to determine when to
check the lubricant.
How to Check Lubricant
Active Transfer Case
A. Fill Plug
B. Drain Plug To get an accurate reading, the
vehicle should be on a level
surface.
If the level is below the bottom of
the fill plug (A) hole, some lubricant
will need to be added. Add enough
lubricant to raise the level to the
bottom of the fill plug (A) hole. Use
care not to overtighten the plug.
When to Change Lubricant
Refer to
Maintenance Schedule on
page 11-2 to determine how often to
change the lubricant.
What to Use
Refer to Recommended Fluids and
Lubricants on page 11-12 to
determine what kind of lubricant
to use.
Front Axle
When to Check and Change
Lubricant
It is not necessary to regularly
check front axle fluid unless a leak
is suspected, or an unusual noise is
heard. A fluid loss could indicate a
problem. Have it inspected and
repaired.
How to Check Lubricant
To get an accurate reading, the
vehicle should be on a level
surface.
Page 364 of 490

Black plate (26,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
10-26 Vehicle Care
A. Fill Plug
B. Drain Plug
.When the differential is cold, add
enough lubricant to raise the
level from 0 mm (0 in) to 3.2 mm
(1/8 in) below the fill
plug (A) hole.
.When the differential is at
operating temperature (warm),
add enough lubricant to raise the
level to the bottom of the fill
plug (A) hole.What to Use
Refer to
Recommended Fluids and
Lubricants on page 11-12 to
determine what kind of lubricant
to use.
Rear Axle
When to Check Lubricant
It is not necessary to regularly
check rear axle fluid unless there is
a leak suspected, or an unusual
noise is heard. A fluid loss could
indicate a problem. Have it
inspected and repaired.
All axle assemblies are filled by
volume of fluid during production.
They are not filled to reach a certain
level. When checking the fluid level
on any axle, variations in the
readings can be caused by factory
fill differences between the minimum
and the maximum fluid volume.
Also, if a vehicle has just been
driven before checking the fluid
level, it may appear lower than
normal because fluid has traveled out along the axle tubes and has
not drained back to the sump area.
Therefore, a reading taken
five minutes after the vehicle has
been driven will appear to have a
lower fluid level than a vehicle that
has been stationary for an hour or
two. Remember that the rear axle
assembly must be supported to get
a true reading.How to Check Lubricant
To get an accurate reading, the
vehicle should be on a level
surface.
Page 365 of 490

Black plate (27,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
Vehicle Care 10-27
The proper level is from 1.0 mm to
19.0 mm (0.04 in to 0.75 in) below
the bottom of the fill plug hole,
located on the rear axle. Add only
enough fluid to reach the proper
level.
Starter Switch Check
{Warning
When you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured.
1. Before starting this check, be sure there is enough room
around the vehicle.
2. Firmly apply both the parking brake and the regular brake.
Do not use the accelerator
pedal, and be ready to turn off
the engine immediately if it
starts. 3. Try to start the engine in each
gear. The vehicle should start
only in P (Park) or N (Neutral).
If the vehicle starts in any other
position, contact your dealer for
service.
Automatic Transmission
Shift Lock Control
Function Check
{Warning
When you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured.
1. Before starting this check, be sure there is enough room
around the vehicle. It should be
parked on a level surface. 2. Firmly apply the parking brake.
Be ready to apply the regular
brake immediately if the vehicle
begins to move.
3. With the engine off, turn the ignition on, but do not start the
engine. Without applying the
regular brake, try to move the
shift lever out of P (Park) with
normal effort. If the shift lever
moves out of P (Park), contact
your dealer for service.Ignition Transmission
Lock Check
While parked, and with the parking
brake set, try to turn the ignition to
LOCK/OFF in each shift lever
position.
.The ignition should turn to
LOCK/OFF only when the shift
lever is in P (Park).
.The ignition key should come
out only in LOCK/OFF.
Contact your dealer if service is
required.
Page 366 of 490

Black plate (28,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
10-28 Vehicle Care
Park Brake and P (Park)
Mechanism Check
{Warning
When you are doing this check,
the vehicle could begin to move.
You or others could be injured
and property could be damaged.
Make sure there is room in front
of the vehicle in case it begins to
roll. Be ready to apply the regular
brake at once should the vehicle
begin to move.
Park on a fairly steep hill, with the
vehicle facing downhill. Keeping
your foot on the regular brake, set
the parking brake.
.To check the parking brake's
holding ability: With the engine
running and the transmission in
N (Neutral), slowly remove foot
pressure from the regular brake
pedal. Do this until the vehicle is
held by the parking brake only.
.To check the P (Park)
mechanism's holding ability:
With the engine running, shift to
P (Park). Then release the
parking brake followed by the
regular brake.
Contact your dealer if service is
required.
Wiper Blade Replacement
Windshield wiper blades should be
inspected for wear or cracking. See
Maintenance Schedule on
page 11-2.
Replacement blades come in
different types and are removed in
different ways.
Front Wiper Blade
Replacement
1. Pull the windshield wiper arm connector away from the
windshield.
2. Squeeze the grooved areas oneach side of the blade, and turn
the blade assembly away from
the arm connector.
3. Install the new blade onto thearm connector and make sure
the grooved areas are fully set in
the locked position.
For the proper type and size, see
Maintenance Replacement Parts on
page 11-14.
Page 367 of 490

Black plate (29,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
Vehicle Care 10-29
Rear Wiper Blade Replacement
1. Lift the wiper blade assembly upand out of the park rest position.
2. Pull the wiper blade assemblyaway from the backglass. The
backglass wiper blade will not
lock in a vertical position, so
care should be used when
pulling it away from the vehicle.
3. Turn the wiper blade assembly, and pull it off of the wiper arm.
Hold the wiper arm in position
and push the blade away from
the wiper arm.
4. Replace the wiper blade.
5. Return the wiper blade assemblyto the park rest position.
Glass Replacement
If the windshield or front side glass
must be replaced, see your dealer
to determine the correct
replacement glass.
Headlamp Aiming
Headlamp aim has been preset and
should need no further adjustment.
If the vehicle is damaged in a crash,
the headlamp aim may be affected.
If adjustment to the headlamps is
necessary, see your dealer.
Page 368 of 490

Black plate (30,1)GMC Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada-
6081505) - 2014 - crc - 4/23/13
10-30 Vehicle Care
Bulb Replacement
For the proper type of replacement
bulbs, seeReplacement Bulbs on
page 10-31.
For any bulb‐changing procedure
not listed in this section, contact
your dealer.
Halogen Bulbs
{Warning
Halogen bulbs have pressurized
gas inside and can burst if you
drop or scratch the bulb. You or
others could be injured. Be sure
to read and follow the instructions
on the bulb package.
Taillamps, Turn Signal,
Stoplamps, and Back-Up
Lamps
A. Stoplamp/Taillamp
B. Taillamp/Turn Signal Lamp
C. Sidemarker Lamp
D. Back-up Lamp
To replace one of these bulbs:
1. Open the liftgate. See Liftgate
on page 2-9.
2. Remove the two screws from the taillamp assembly.
3. Pull the taillamp assembly rearward until you disengage the
inner pins on the taillamp
assembly from the vehicle.
4. Turn the bulb socket counterclockwise to remove it
from the taillamp assembly.
5. Pull the old bulb straight out from the bulb socket.
6. Press a new bulb into the bulb socket.