ECU GMC YUKON XL 2018 Service Manual

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/20/17
186 Climate Controls
Maintenance Passenger Compartment
Air Filter The filter reduces the dust, pollen,
and other airborne irritants from
outside air that is pulled into the
vehicle.
The filter should be replaced as part
of routine scheduled maintenance.
See Maintenance Schedule 0 370 .
To find out what type of filter to use,
see Maintenance Replacement
Parts 0 380 .
1. Open the glove box completely. 2. Disconnect the glove box door
damper string from the glove
box door assembly. A pen or
pencil may be inserted through
the end of the damper string to
prevent the string from slipping
inside the door assembly.
3. Remove the six screws and
remove the access plate. 4. Release the two tabs holding
the service door. Open the
service door and remove the
old filter.
5. Install the new air filter.
6. Close the service door and
secure the tabs.
7. Reverse the steps to reinstall
the glove box.
See your dealer if additional
assistance is needed.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
Driving and Operating 193.
Read all the information about
four-wheel-drive vehicles in this
manual.
.
Remove any underbody air
deflector, if equipped. Re-attach
the air deflector after off-road
driving.
.
Know the local laws that apply to
off-road driving.
To gain more ground clearance if
needed, it may be necessary to
remove the front fascia lower air
dam, if equipped. However, driving
without the air dam reduces fuel
economy.
Caution
Operating the vehicle for
extended periods without the front
fascia lower air dam installed can
cause improper airflow to the
engine. Reattach the front fascia
air dam after off-road driving. Loading the Vehicle for
Off-Road Driving
{ Warning.
Unsecured cargo on the
load floor can be tossed
about when driving over
rough terrain. You or your
passengers can be struck
by flying objects. Secure the
cargo properly.
.
Keep cargo in the cargo
area as far forward and as
low as possible. The
heaviest things should be
on the floor, forward of the
rear axle.
.
Heavy loads on the roof
raise the vehicle's center of
gravity, making it more likely
to roll over. You can be
seriously or fatally injured if
the vehicle rolls over. Put
heavy loads inside the
cargo area, not on the roof. For more information about loading
the vehicle, see Vehicle Load Limits
0 200 and Tires 0 320 .
Environmental Concerns .
Always use established trails,
roads, and areas that have been
set aside for public off-road
recreational driving and obey all
posted regulations.
.
Do not damage shrubs, flowers,
trees, or grasses or disturb
wildlife.
.
Do not park over things that
burn. See Parking over Things
That Burn 0 214 .
Driving on Hills Driving safely on hills requires good
judgment and an understanding of
what the vehicle can and cannot do.
{ Warning
Many hills are simply too steep
for any vehicle. Driving up hills
can cause the vehicle to stall.
Driving down hills can cause loss
(Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
204 Driving and Operating Using heavier suspension
components to get added
durability might not change the
weight ratings. Ask your dealer
to help load the vehicle the
right way.
{ Warning
Things you put inside the
vehicle can strike and injure
people in a sudden stop or
turn, or in a crash. .
Put things in the cargo
area of the vehicle. Try to
spread the weight evenly..
Never stack heavier
things, like suitcases,
inside the vehicle so that
some of them are above
the tops of the seats.
.
Do not leave an
unsecured child restraint
in the vehicle.
(Continued) Warning (Continued) .
When you carry
something inside the
vehicle, secure it
whenever you can. .
Do not leave a seat
folded down unless you
need to.
There is also important loading
information for off-road driving in
this manual. See “ Loading Your
Vehicle for Off-Road Driving ”
under Off-Road Driving 0 192 .Starting and
Operating New Vehicle Break-In CautionThe vehicle does not need an
elaborate break-in. But it will
perform better in the long run if
you follow these guidelines:
.
Keep the vehicle speed at
88 km/h (55 mph) or less for
the first 805 km (500 mi).
.
Do not drive at any one
constant speed, fast or slow,
for the first 805 km (500 mi).
Do not make full-throttle
starts. Avoid downshifting to
brake or slow the vehicle.
.
Avoid making hard stops for
the first 322 km (200 mi) or
so. During this time the new
brake linings are not yet
broken in. Hard stops with
new linings can mean
(Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
Driving and Operating 211thermostat in the plug end of the
cord, which will prevent engine
heater operation at temperatures
above − 18 °C (0 °F).
To Use the Engine Heater 1. Turn off the engine.
2. Open the hood and unwrap the
electrical cord. The cord is by
the left front fender, next to the
engine compartment fuse
block.
Check the heater cord for
damage. If it is damaged, do
not use it. See your dealer for
a replacement. Inspect the
cord for damage yearly.
3. Plug the cord into a normal,
grounded 110-volt AC outlet. { WarningImproper use of the heater cord
or an extension cord can damage
the cord and may result in
overheating and fire.
.
Plug the cord into a
three-prong electrical utility
receptacle that is protected
by a ground fault detection
function. An ungrounded
outlet could cause an
electric shock.
.
Use a weatherproof,
heavy-duty, 15 amp-rated
extension cord if needed.
Failure to use the
recommended extension
cord in good operating
condition, or using a
damaged heater or
extension cord, could make
(Continued) Warning (Continued) it overheat and cause a fire,
property damage, electric
shock, and injury.
.
Do not operate the vehicle
with the heater cord
permanently attached to the
vehicle. Possible heater
cord and thermostat
damage could occur.
.
While in use, do not let the
heater cord touch vehicle
parts or sharp edges. Never
close the hood on the
heater cord.
.
Before starting the vehicle,
unplug the cord, reattach
the cover to the plug, and
securely fasten the cord.
Keep the cord away from
any moving parts.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
260 Driving and Operating Warning (Continued).
Also adjust the climate
control system to a setting
that brings in only outside
air. See “ Climate Control
Systems ” in the Index.
For more information about
carbon monoxide, see Engine
Exhaust 0 215 .
Towing a trailer requires a certain
amount of experience. The
combination you are driving is
longer and not as responsive as the
vehicle itself. Get acquainted with
the handling and braking of the rig
before setting out for the open road.
The structure, tires, and brakes of
the trailer must be rated to carry the
load. Inadequate trailer equipment
can cause the combination to
operate in an unexpected or unsafe
manner.
Before starting, check all trailer hitch
parts and attachments, safety
chains, electrical connectors, lamps,
tires, and mirrors. Get familiar with the handling and braking of the rig.
If the trailer has electric brakes, start
the combination moving and then
apply the trailer brake controller by
hand to be sure the brakes work.
During the trip, check occasionally
to be sure that the load is secure
and the lamps and any trailer
brakes still work.
Following Distance Stay at least twice as far behind the
vehicle ahead as you would when
driving the vehicle without a trailer.
This can help to avoid heavy
braking and sudden turns.
Passing More passing distance is needed
when towing a trailer. The
combination will not accelerate as
quickly and is longer so it is
necessary to go much farther
beyond the passed vehicle before
returning to the lane.
Backing Up
Hold the bottom of the steering
wheel with one hand. To move the
trailer to the left, move that hand to the left. To move the trailer to the
right, move your hand to the right.
Always back up slowly and,
if possible, have someone
guide you.
Making Turns
CautionMaking very sharp turns while
trailering could cause the trailer to
come in contact with the vehicle.
The vehicle could be damaged.
Avoid making very sharp turns
while trailering.
When turning with a trailer, make
wider turns than normal. Do this so
the trailer will not strike soft
shoulders, curbs, road signs, trees,
or other objects. Avoid jerky or
sudden maneuvers. Signal well in
advance.
If the trailer turn signal bulbs burn
out, the arrows on the instrument
cluster will still flash for turns. It is
important to check occasionally to
be sure the trailer bulbs are still
working.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/20/17
294 Vehicle Care 3. Fill the coolant surge tank with
the proper mixture to the full
cold mark.
4. With the coolant surge tank
pressure cap off, start the
engine and let it run until the
engine coolant temperature
gauge indicates approximately
90 °C (195 °F).
By this time, the coolant level
inside the coolant surge tank
may be lower. If the level is
lower, add more of the proper
mixture to the coolant surge
tank until the level reaches the
full cold mark.
5. Replace the pressure cap
tightly.
6. Verify coolant level after the
engine is shut off and the
coolant is cold. If necessary,
repeat coolant fill procedure
Steps 1 – 6. CautionIf the pressure cap is not tightly
installed, coolant loss and engine
damage may occur. Be sure the
cap is properly and tightly
secured.
Engine Overheating CautionDo not run the engine if there is a
leak in the engine cooling system.
This can cause a loss of all
coolant and can damage the
system and vehicle. Have any
leaks fixed right away.
The vehicle has several indicators
to warn of engine overheating.
There is a coolant temperature
gauge in the vehicle's instrument
cluster. See Engine Coolant
Temperature Gauge 0 138 . In addition, there are ENGINE
OVERHEATED STOP ENGINE,
ENGINE OVERHEATED IDLE
ENGINE, and ENGINE POWER IS
REDUCED messages in the Driver
Information Center (DIC).
If the decision is made not to lift the
hood when this warning appears,
get service help right away. See
Roadside Assistance Program
0 390 .
If the decision is made to lift the
hood, make sure the vehicle is
parked on a level surface.
Check to see if the engine cooling
fan(s) are running. If the engine is
overheating, the fans should be
running. If they are not, do not
continue to run the engine. Have the
vehicle serviced.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/20/17
304 Vehicle Care
2. Lift up on the latch in the
middle of the wiper blade
where the wiper arm attaches.
3. With the latch open, pull the
wiper blade down toward the
windshield far enough to
release it from the J-hooked
end of the wiper arm.
4. Remove the wiper blade.
Allowing the wiper blade arm to
touch the windshield when no
wiper blade is installed could
damage the windshield. Any
damage that occurs would not
be covered by the vehicle warranty. Do not allow the
wiper blade arm to touch the
windshield.
5. Reverse Steps 1 – 3 for wiper
blade replacement.
Rear Wiper Blade Replacement To replace the rear wiper blade:
1. With the rear wiper in the off
position, open the liftglass to
access the rear wiper arm/
blade.
The rear wiper blade will not
lock in a vertical position so
care should be used when
pulling it away from the vehicle. 2. Push the release lever (2) to
disengage the hook and push
the wiper arm (1) out of the
blade assembly (3).
3. Push the new blade assembly
securely in the wiper arm hook
until the release lever clicks
into place.
4. Return the wiper arm and
blade assembly to the rest
position on the glass.
Glass Replacement If the windshield or front side glass
must be replaced, see your dealer
to determine the correct
replacement glass.
Windshield Replacement HUD System
The windshield is part of the HUD
system. If the windshield must be
replaced, get one that is designed
for HUD or the HUD image may
look out of focus.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/20/17
340 Vehicle Care CautionThe wrong wheel can also cause
problems with bearing life, brake
cooling, speedometer or
odometer calibration, headlamp
aim, bumper height, vehicle
ground clearance, and tire or tire
chain clearance to the body and
chassis.
Used Replacement Wheels
{ WarningReplacing a wheel with a used
one is dangerous. How it has
been used or how far it has been
driven may be unknown. It could
fail suddenly and cause a crash.
When replacing wheels, use a
new GM original equipment
wheel. Tire Chains
{ WarningIf the vehicle has 265/65R18,
P265/65R18, P275/55R20,
or P285/45R22 size tires, do not
use tire chains. There is not
enough clearance. Tire chains
used on a vehicle without the
proper amount of clearance can
cause damage to the brakes,
suspension, or other vehicle
parts. The area damaged by the
tire chains could cause loss of
control and a crash.
Use another type of traction
device only if its manufacturer
recommends it for the vehicle's
tire size combination and road
conditions. Follow that
manufacturer's instructions. To
avoid vehicle damage, drive slow
and readjust or remove the
traction device if it is contacting
the vehicle. Do not spin the
wheels.
(Continued) Warning (Continued) If traction devices are used, install
them on the rear tires.
CautionIf the vehicle has P255/70R17 or
P265/70R17 size tires, use tire
chains only where legal and only
when necessary. Use chains that
are the proper size for the tires.
Install them on the rear tires only.
Do not use chains on the front
tires. Tighten them as tightly as
possible with the ends securely
fastened. Drive slowly and follow
the chain manufacturer's
instructions. If the chains contact
the vehicle, stop and retighten
them. If the contact continues,
slow down until it stops. Driving
too fast or spinning the wheels
with chains on will damage the
vehicle.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/20/17
350 Vehicle Care 3. Assemble the two jack handle
extensions (4) and wheel
wrench (5).
4. Insert the open end of the
extension (7) through the hole
in the rear bumper (8) (hoist
shaft access hole).
5. Raise the tire part way upward.
Make sure the retainer is
seated in the wheel opening.
6. Raise the tire fully against the
underside of the vehicle by
turning the wheel wrench
clockwise until you hear two
clicks or feel it skip twice. The
cable cannot be overtightened. 7. Make sure the tire is stored
securely. Push, pull, and then
try to turn the tire. If the tire
moves, use the wheel wrench
to tighten the cable.
8. Reinstall the spare tire lock.
9. Reinstall the hoist shaft access
cover.
If equipped, reinstall the hitch
cover and turn the retainers
clockwise.
To store the tools:
1. Return the tools (wheel
wrench, jack handle, and jack
handle extensions) to the
tool bag. 2. Assemble the wheel blocks
and jack together with the
wing nut.
3. Position the jack and wheel
blocks in the driver side trim
panel over the wheelhouse.
4. Turn the jack knob clockwise
until the jack is secured tight in
the mounting bracket. Be sure
to position the holes in the
base of the jack onto the pin in
the mounting bracket.
5. Use the retaining bracket to
fasten the tool bag on the stud
and turn the wing nut clockwise
to secure.
6. Close the trim panel door.
Full-Size Spare Tire If this vehicle came with a full-size
spare tire, it was fully inflated when
new, however, it can lose air over
time. Check the inflation pressure
regularly.
See Tire Pressure 0 327 and
Vehicle Load Limits 0 200 . For

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/20/17
Vehicle Care 355Jumper Cable Removal
Reverse the sequence exactly when
removing the jumper cables.
After starting the disabled vehicle
and removing the jumper cables,
allow it to idle for several minutes.
Towing the Vehicle CautionIncorrectly towing a disabled
vehicle may cause damage. The
damage would not be covered by
the vehicle warranty.
Do not lash or hook to
suspension components. Use the
proper straps around the tires to
secure the vehicle.
Use only a flatbed tow truck for
towing a disabled vehicle. Never
use a sling type lift or damage will
occur. Use ramps to help reduce
approach angles if necessary.
A towed vehicle should have its
drive wheels off the ground.
Consult a professional towing
service if the disabled vehicle must
be towed. Front Attachment Points
The vehicle is equipped with
specific attachment points to be
used to pull the vehicle onto a
flatbed car carrier from a flat road
surface. Do not use these
attachment points to pull the vehicle
from snow, mud or sand.
Recreational Vehicle
Towing Recreational vehicle towing means
towing the vehicle behind another
vehicle, such as a motor home. The
two most common types of
recreational vehicle towing are