V4 mode GMC YUKON DENALI 2007 Repair Manual

Traction Control Operation
The traction control system is part of the
StabiliTrak®system. Traction control limits wheel
spin by reducing engine power to the wheels
(engine speed management) and by applying
brakes to each individual wheel (brake-traction
control) as necessary.
The traction control system is enabled
automatically when you start your vehicle. It will
activate and the StabiliTrak
®light will ash if
it senses that any of the wheels are spinning or
beginning to lose traction while driving. If you turn
off traction control, only the brake-traction
control portion of traction control will work. The
engine speed management will be disabled. In this
mode, engine power is not reduced automatically
and the driven wheels can spin more freely.
This can cause the brake-traction control to
activate constantly.
Notice:If you allow the wheel(s) of one axle
to spin excessively while the StabiliTrak
®, ABS
and brake warning lights and the SERVICE
STABILITRAK message are displayed,
you could damage the transfer case. The
repairs would not be covered by your warranty.Reduce engine power and do not spin the
wheel(s) excessively while these lights and this
message are displayed.
The traction control system may activate on
dry or rough roads or under conditions such as
heavy acceleration while turning or abrupt
upshifts/downshifts of the transmission. When
this happens, you may notice a reduction in
acceleration, or may hear a noise or vibration.
This is normal.
If your vehicle is in cruise control when the system
activates, the StabiliTrak
®light will ash and the
cruise control will automatically disengage.
When road conditions allow you to use cruise
again, you may re-engage the cruise control. See
Cruise Control on page 200.
StabiliTrak
®may also turn off automatically if it
determines that a problem exists with the system.
If the problem does not clear itself after restarting
the vehicle, you should see your dealer for
service.
352

Level Control
Automatic Level Control
The automatic level control rear suspension is
available on light-duty vehicles and comes
as a part of the Autoride
®suspension, if equipped.
This type of level control is fully automatic and
will provide a better leveled riding position as well
as better handling under a variety of passenger
and loading conditions. An air compressor
connected to the rear shocks will raise or lower
the rear of the vehicle to maintain proper vehicle
height. The system is activated when the
ignition key is turned to RUN and will automatically
adjust vehicle height thereafter. The system
may exhaust (lower vehicle height) for up to
ten minutes after the ignition key has been turned
off. You may hear the air compressor operating
when the height is being adjusted.
If a weight-distributing hitch is being used, it is
recommended to allow the shocks to inate,
thereby leveling the vehicle prior to adjusting the
hitch.
Autoride®
The Autoride®feature provides improved vehicle
ride and handling under a variety of passenger and
loading conditions.
The system is fully automatic and uses a computer
controller to continuously monitor vehicle speed,
wheel to body position, lift/dive and steering
position of the vehicle. The controller then sends
signals to each shock absorber to independently
adjust the damping level to provide the optimum
vehicle ride.
Autoride
®also interacts with the tow/haul mode
that, when activated, will provide additional control
of the shock absorbers. This additional control
results in better ride and handling characteristics
when the vehicle is loaded or towing a trailer. See
“Tow/Haul Mode” underTowing a Trailer on
page 400for more information.
399

If You Do Decide To Pull A Trailer
If you do, here are some important points:
There are many different laws, including speed
limit restrictions, having to do with trailering.
Make sure your rig will be legal, not only where
you live but also where you’ll be driving. A
good source for this information can be state
or provincial police.
Consider using a sway control. See “Hitches”
later in this section.
Don’t tow a trailer at all during the rst
500 miles (800 km) your new vehicle is driven.
Your engine, axle or other parts could be
damaged.
Then, during the rst 500 miles (800 km) that
you tow a trailer, don’t drive over 50 mph
(80 km/h) and don’t make starts at full throttle.
This helps your engine and other parts of
your vehicle wear in at the heavier loads.
You can tow in DRIVE (D). You may want to
shift the transmission to THIRD (3) or, if
necessary, a lower gear selection if the
transmission shifts too often (e.g., under heavy
loads and/or hilly conditions). See “Tow/Haul
Mode” underTowing a Trailer on page 400.Three important considerations have to do with
weight:
the weight of the trailer
the weight of the trailer tongue
and the weight on your vehicle’s tires
Tow/Haul Mode
The Tow/Haul feature assists when pulling a
heavy trailer or a large or heavy load. The purpose
of the Tow/Haul mode is to:
Reduce the frequency and improve the
predictability of transmission shifts when
pulling a heavy trailer or a large or heavy load.
Provide the same solid shift feel when pulling a
heavy trailer or a large or heavy load as when
the vehicle is unloaded.
Improve control of vehicle speed while
requiring less throttle pedal activity when
pulling a heavy trailer or a large or heavy load.
401

Press this button at the end of the shift lever to
enable tow/haul mode.
When the button is pressed, a light on the
instrument panel will illuminate to indicate that
Tow/Haul has been selected. Tow/Haul may
be turned off by pressing the button again, at
which time the indicator light on the instrument
panel will turn off. The vehicle will automatically
turn off tow/haul every time it is started.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
Combination Weight Rating (GCWR). See “Weight
of the Trailer” later in this 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 benet 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.
402

Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to
pull a trailer are all important. It can also depend
on any special equipment that you have on
your vehicle, and the amount of tongue weight the
vehicle can carry. See “Weight of the Trailer
Tongue” later in this section for more information.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 chart to determine how much
your vehicle can weigh, based upon your vehicle
model and options.
Vehicle Axle Ratio Maximum Trailer Weight **GCWR
Yukon Denali 3.42 7,400 lbs (3 356 kg) 14,000 lbs (6 350 kg)
Yukon XL Denali 3.42 7,700 lbs (3 493 kg) 14,000 lbs (6 350 kg)
**The Gross Combination Weight Rating (GCWR) in the total allowable weight of the completely loaded vehicle and
trailer including any passengers, cargo, equipment and conversions. The GCWR for your vehicle should not be
exceeded.
You can ask your dealer for our trailering
information or advice, or you can write us at the
address listed in your Warranty and Owner
Assistance Information Booklet.In Canada, write to:
General Motors of Canada Limited
Customer Communication Centre, 163-005
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7
403

After you have loaded the trailer, weigh the trailer
and then the tongue separately, to see if the
weights are proper. If they are not, you may be
able to get them right by moving some items
around in the trailer.
Trailering may be limited by the vehicle’s ability
to carry tongue weight. Tongue weight cannot
cause the vehicle to exceed the GVWR (Gross
Vehicle Weight Rating) or the RGAWR (Rear
Gross Axle Weight Rating). The effect of additional
weight may reduce your trailering capacity more
than the total of the additional weight.
Consider the following example:
A vehicle model base weight is 5,500 lbs
(2 495 kg); 2,800 lbs (1 270 kg) at the front
axle and 2,700 lbs (1 225 kg) at the rear axle.
It has a GVWR of 7,200 lbs (3 266 kg), a
RGAWR of 4,000 lbs (1 814 kg) and a GCWR
(Gross Combination Weight Rating) of
14,000 lbs (6 350 kg).The trailer rating should be:
You can expect tongue weight to be at least
10 percent of trailer weight (850 lbs (386 kg)) and
because the weight is applied well behind the
rear axle, the effect on the rear axle will be
greater than just the weight itself, as much as
1.5 times as much. The weight at the rear
axle could be 850 lbs (386 kg) X 1.5 = 1,275 lbs
(578 kg). Since the rear axle already weighs
2,700 lbs (1 225 kg), adding 1,275 lbs (578 kg)
brings the total to 3,975 lbs (1 803 kg).
This is very close to, but within the limit for
RGAWR as well. The vehicle is set to trailer up
to 8,500 lbs (3 856 kg).
405

Turn Signals When Towing a Trailer
The arrows on your instrument panel will
ash whenever you signal a turn or lane change.
Properly hooked up, the trailer lamps will also
ash, telling other drivers you’re about to
turn, change lanes or stop.
When towing a trailer, the arrows on your
instrument panel will ash for turns even if the
bulbs on the trailer are burned out. Thus, you may
think drivers behind you are seeing your signal
when they are not. It’s important to check
occasionally to be sure the trailer bulbs are still
working.
Driving On Grades
Reduce speed and shift to a lower gearbefore
you start down a long or steep downgrade. If you
don’t shift down, you might have to use your
brakes so much that they would get hot and no
longer work well.You can tow in DRIVE (D). You may want to shift
the transmission to THIRD (3) or, if necessary,
a lower gear selection if the transmission shifts
too often (e.g., under heavy loads and/or hilly
conditions).
You may also want to activate the tow/haul mode
if the transmission shifts too often. See “Tow/Haul
Mode” underTowing a Trailer on page 400.
When towing at high altitude on steep uphill
grades, consider the following: Engine coolant at
or near sea level will boil at a lower temperature
than at higher altitudes. If you turn your engine
off immediately after towing at high altitude
on steep uphill grades, your vehicle may show
signs similar to engine overheating. To avoid this,
let the engine run while parked (preferably on
level ground) with the automatic transmission
in PARK (P) for a few minutes before turning the
engine off. If you do get the overheat warning,
seeEngine Overheating on page 448.
411

Trailer Wiring Harness
Heavy-Duty Trailer Wiring Package
Your vehicle is equipped with the seven-wire
trailer towing harness. This harness with a
seven-pin universal heavy-duty trailer connector is
attached to the rear bumper beam. It is located
next to the integrated trailer hitch.The seven-wire harness contains the following
trailer circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Red w/ Black Stripe: Battery Feed*
Dark Blue: Trailer Brake*
*The fuses for these two circuits are installed in
the underhood electrical center, but the circuits are
not connected. They should be installed by your
dealer or a qualied service center.
If you are charging a remote (non-vehicle) battery,
press the tow/haul mode button located at the
end of the shift lever. This will boost the vehicle
system voltage and properly charge the battery.
If the trailer is too light for tow/haul mode, you can
turn on the headlamps as a second way to
boost the vehicle system and charge the battery.
414

Service........................................................ 420
Accessories and Modications................... 421
California Proposition 65 Warning.............. 421
Doing Your Own Service Work.................. 422
Adding Equipment to the Outside
of Your Vehicle...................................... 423
Fuel............................................................. 423
Gasoline Octane........................................ 423
Gasoline Specications.............................. 424
California Fuel........................................... 424
Additives................................................... 424
Fuels in Foreign Countries........................ 425
Filling the Tank......................................... 426
Filling a Portable Fuel Container............... 428
Checking Things Under the Hood.............. 428
Hood Release........................................... 429
Engine Compartment Overview.................. 430
Engine Oil................................................. 432
Engine Oil Life System.............................. 435Engine Air Cleaner/Filter............................ 437
Automatic Transmission Fluid.................... 440
Engine Coolant.......................................... 445
Coolant Surge Tank Pressure Cap............ 448
Engine Overheating................................... 448
Overheated Engine Protection
Operating Mode..................................... 450
Cooling System......................................... 451
Engine Fan Noise..................................... 456
Power Steering Fluid................................. 457
Windshield Washer Fluid........................... 458
Brakes...................................................... 459
Battery...................................................... 463
Jump Starting............................................ 464
All-Wheel Drive........................................... 469
Rear Axle.................................................... 470
Front Axle................................................... 471
Headlamp Aiming........................................ 473
Section 5 Service and Appearance Care
417

Coolant Surge Tank Pressure Cap
Notice:If the pressure cap is not tightly
installed, coolant loss and possible engine
damage may occur. Be sure the cap is properly
and tightly secured.
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. SeeEngine
Compartment Overview on page 430for more
information on location.
Engine Overheating
You will nd a coolant temperature gage on your
vehicle’s instrument panel. SeeEngine Coolant
Temperature Gage on page 236.
In addition, you will nd an ENGINE
OVERHEATED STOP ENGINE, ENGINE
OVERHEATED IDLE ENGINE, and an ENGINE
POWER IS REDUCED message in the Driver
Information Center (DIC) on the instrument panel.
SeeDIC Warnings and Messages on page 252.
If Steam Is Coming From Your Engine
{CAUTION:
Steam from an overheated engine can burn
you badly, even if you just open the hood.
Stay away from the engine if you see or
hear steam coming from it. Just turn it off
and get everyone away from the vehicle
until it cools down. Wait until there is no
sign of steam or coolant before you open
the hood.
If you keep driving when your engine is
overheated, the liquids in it can catch re.
You or others could be badly burned.
Stop your engine if it overheats, and get
out of the vehicle until the engine is cool.
SeeOverheated Engine Protection
Operating Mode on page 450for
information on driving to a safe place
in an emergency.
448