2010 GMC YUKON DENALI trailer

Starting and Operating Your
Vehicle
New Vehicle Break-In
Notice:The vehicle does not need an elaborate
break-in. But it will perform better in the long run if
you follow these guidelines:
.Keep your speed at 55 mph (88 km/h) or less
for the first 500 miles (805 km).
.Do not drive at any one constant speed,
fast or slow, for the first 500 miles
(805 km). Do not make full-throttle starts.
Avoid downshifting to brake or slow the
vehicle.
.Avoid making hard stops for the first
200 miles (322 km) or so. During this time
the new brake linings are not yet broken in.
Hard stops with new linings can mean
premature wear and earlier replacement.
Follow this breaking-in guideline every time
you get new brake linings.
.Do not tow a trailer during break-in.
See Towing a Trailer
on page 5‑42for the
trailer towing capabilities of the vehicle and
more information.
Following break‐in, engine speed and load can be
gradually increased.
3-24

Automatic Transmission Operation
The vehicle has a Hydra-Matic®6L80 automatic
transmission, and has an electronic shift position
indicator within the instrument panel cluster.
The electronic shift position indicator displays when
the shift lever is moved out of P (Park).
There are several different positions for the shift lever.
Light Duty 6‐Speed Automatic Transmission Shown (Heavy Duty 6‐Speed Similar)
See “Range Selection Mode” later in this section.
P (Park) : This position locks your rear wheels. It is the
best position to use when you start the engine because
the vehicle cannot move easily. When parked on a hill, especially when the vehicle has
a heavy load, you may notice an increase in the effort
to shift out of P (Park). See Torque Lock (Automatic
Transmission) under
Shifting Into Park
on page 3‑37for more information.
{WARNING:
It is dangerous to get out of the vehicle if the shift
lever is not fully in P (Park) with the parking brake
firmly set. The vehicle can roll.
Do not leave the vehicle when the engine is
running unless you have to. If you have left the
engine running, the vehicle can move suddenly.
You or others could be injured. To be sure the
vehicle will not move, even when you are on fairly
level ground, always set the parking brake and
move the shift lever to P (Park). See Shifting Into
Park
on page 3‑37. If you are pulling a trailer,
see Towing a Trailer on page 5‑42.
3-30

R (Reverse) :Use this gear to back up.
Notice: Shifting to R (Reverse) while the vehicle is
moving forward could damage the transmission.
The repairs would not be covered by the vehicle
warranty. Shift to R (Reverse) only after the vehicle
is stopped.
To rock the vehicle back and forth to get out of snow,
ice, or sand without damaging the transmission, see If
Your Vehicle is Stuck in Sand, Mud, Ice, or Snow
on
page 5‑29.
N (Neutral) : In this position, the engine does not
connect with the wheels. To restart the engine when the
vehicle is already moving, use N (Neutral) only. Also,
use N (Neutral) when the vehicle is being towed.
{WARNING:
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless your
foot is firmly on the brake pedal, the vehicle could
move very rapidly. You could lose control and hit
people or objects. Do not shift into a drive gear
while the engine is running at high speed. Notice:
Shifting out of P (Park) or N (Neutral) with
the engine running at high speed may damage the
transmission. The repairs would not be covered by
the vehicle warranty. Be sure the engine is not
running at high speed when shifting the vehicle.
D (Drive) : This position is for normal driving. It provides
the best fuel economy for the vehicle. If you need more
power for passing, and you are:
.Going less than about 35 mph (55 km/h), push the
accelerator pedal about halfway down.
.Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
D (Drive) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road driving.
You may want to shift the transmission to a lower gear
selection if the transmission shifts too often.
Downshifting the transmission in slippery road
conditions could result in skidding, see “Skidding”
under Loss of Control on page 5‑11.
3-31

Range Selection Mode
On vehicles with a Range Selection Mode, this feature
may be used to control the vehicle's transmission.
To use this feature, do the following:1. Move the shift lever to the M (Manual Mode).
2. Press the plus/minus button, to upshift or downshift selecting the desired range of gears for current
driving conditions. When in M (Manual Mode) a number displays next
to the M, indicating the current gear that has been
selected. The number displayed in the gear indicator is
the highest gear that can be used. However, the vehicle
can automatically shift to lower gears as it adjusts to
driving conditions. This means that all gears below
that number are available. When 5 (Fifth) is selected,
1 (First) through 5 (Fifth) gears are automatically shifted
by the vehicle, but 6 (Sixth) cannot be used until the
plus/minus button located on the steering column lever
is used to change to the gear.
Range Selection Mode controls the vehicle and engine
speed while driving down a hill or towing a trailer,
by allowing you to select a desired range of gears.
Grade Braking is not available when the Range
Selection Mode is active. See
Tow/Haul Mode
on
page 3‑34for more information.
While using the Range Selection Mode, Cruise Control
and the Tow/Haul mode can be used.
3-33

Tow/Haul Mode
The vehicle has a tow/haul mode. The tow/haul mode
adjusts the transmission shift pattern to reduce shift
cycling, providing increased performance, vehicle
control, and transmission cooling when towing or
hauling heavy loads.Press the button located on the end of the shift lever to
turn the tow/haul on or off. When the tow/haul is on, a
light on the instrument panel cluster will come on.
See
Tow/Haul Mode Light
on page 4‑40for more
information.
Also see “Tow Haul Mode” underTowing a Trailer
on
page 5‑42for more information.
The tow/haul mode works with the Autoride
®feature,
if the vehicle has this, to enhance the ride when
trailering or with a loaded vehicle. See Autoride
®on
page 5‑41.
3-34

Grade Braking
The Grade Braking shift modes can be activated by
pressing the button on the end of the shift control lever.
While in Range Selection Mode , Grade Braking is
deactivated allowing the driver to select a desired range
of gears.
Grade Braking is only active while the Tow/Haul Mode
is selected and you are not in the Range Selection
Mode. See“Tow/Haul Mode listed previously and
Automatic Transmission Operation
on page 3‑30for
more information on the Range Selection Mode. Grade
Braking assists in maintaining desired vehicle speeds
when driving on downhill grades by automatically
implementing a shift schedule that utilizes the engine
and transmission to slow the vehicle. This reduces wear
on the braking system and increases control of the
vehicle. Grade Braking monitors vehicle speed,
acceleration, engine torque and brake pedal usage.
Using this information, it detects when the vehicle is on
a downhill grade and the driver desires to slow the
vehicle by pressing the brake.
Also see Towing a Trailer
on page 5‑42for more
information.
Cruise Grade Braking
Cruise Grade Braking assists when driving on a
downhill grade. It maintains vehicle speed by
automatically implementing a shift schedule that uses
the engine and the transmission to slow the vehicle.
Cruise Grade Braking operates while Cruise Control is
engaged in Tow/Haul mode to assist in maintaining
vehicle speed under loaded vehicle conditions.
It utilizes vehicle acceleration and deviation from
desired speed to determine the correct gear for the
operating condition. If vehicle speed is above the
desired speed the transmission will downshift to slow
the vehicle. If vehicle speed is near or below desired
speed the trans will upshift, allowing vehicle speed to
increase.
While in the Range Select Mode (RSM) mode, cruise
grade braking is not available.
See Automatic Transmission Operation on page 3‑30.
3-35

Parking Brake
Set the parking brake by holding the regular brake
pedal down, then pushing down the parking brake
pedal.If the ignition is on, the brake system warning light
will come on. See
Brake System Warning Light
on
page 4‑32.
Notice: Driving with the parking brake on can
overheat the brake system and cause premature
wear or damage to brake system parts. Make sure
that the parking brake is fully released and the
brake warning light is off before driving.
To release the parking brake, hold the regular brake
pedal down, then push down momentarily on the
parking brake pedal until you feel the pedal release.
Slowly pull your foot up off the park brake pedal. If the
parking brake is not released when you begin to drive,
the brake system warning light will flash and a chime
will sound warning you that the parking brake is still on.
If you are towing a trailer and are parking on a hill,
see Towing a Trailer on page 5‑42.
3-36

Shifting Into Park
{WARNING:
It can be dangerous to get out of the vehicle if the
shift lever is not fully in P (Park) with the parking
brake firmly set. The vehicle can roll. If you have
left the engine running, the vehicle can move
suddenly. You or others could be injured. To be
sure the vehicle will not move, even when you are
on fairly level ground, use the steps that follow.
If you are pulling a trailer, seeTowing a Trailer
on
page 5‑42
.
1. Hold the brake pedal down, then set the parking brake.
2. Move the shift lever into the P (Park) position by pulling the shift lever toward you and moving it up
as far as it will go.
3. Turn the ignition key to LOCK/OFF.
4. Remove the key and take it with you. If you can leave the vehicle with the ignition key in your hand,
the vehicle is in P (Park).
Leaving the Vehicle With the Engine
Running
{WARNING:
It can be dangerous to leave the vehicle with the
engine running. The vehicle could move suddenly
if the shift lever is not fully in P (Park) with the
parking brake firmly set. And, if you leave the
vehicle with the engine running, it could overheat
and even catch fire. You or others could be
injured. Do not leave the vehicle with the engine
running.
If you have to leave the vehicle with the engine running,
be sure the vehicle is in P (Park) and the parking brake
is firmly set. After the shift lever is moved into P (Park),
hold the regular brake pedal down. Then, see if you can
move the shift lever away from P (Park) without first
pulling it toward you. If you can, it means that the shift
lever was not fully locked into P (Park).
3-37