2008 GMC ACADIA trailer

Starting and Operating Your
Vehicle
New Vehicle Break-In
Notice:Your vehicle does not need an elaborate
break-in. But it will perform better in the long run if
you follow these guidelines:
If you have all-wheel drive, keep your speed at
55 mph (88 km/h) or less for the rst 500 miles
(805 km).
Do not drive at any one constant speed, fast or
slow, for the rst 500 miles (805 km). Do not
make full-throttle starts. Avoid downshifting to
brake or slow the vehicle.
Avoid making hard stops for the rst 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. SeeTowing a
Trailer on page 4-30for the trailer towing
capabilities of your vehicle and more
information.
Following break-in, engine speed and load can be
gradually increased.
2-25

Automatic Transmission Operation
Your vehicle has an electronic shift position indicator
within the instrument panel cluster.
When using the Electronic Range Select Mode a
number will display next to the L, indicating the current
gear that has been selected.
See Electronic Range Select mode in this section for
more information.
Your automatic transmission has a shift lever located on
the console between the seats.
PARK (P):This position locks your front wheels. It is
the best position to use when you start your engine
because your vehicle cannot move easily.{CAUTION:
It is dangerous to get out of your vehicle if the
shift lever is not fully in PARK (P) with the
parking brake rmly set. Your vehicle can roll.
Do not leave your 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 your vehicle will not move, even when
you are on fairly level ground, always set your
parking brake and move the shift lever to
PARK (P). SeeShifting Into PARK (P) on
page 2-36. If you are pulling a trailer, see
Towing a Trailer on page 4-30.
2-30

DRIVE (D):This position is for normal driving. It
provides the best fuel economy for your vehicle. If you
need more power for passing, and you are:
Going less than 35 mph (56 km/h), push your
accelerator pedal about halfway down.
Going about 35 mph (56 km/h) or more, push the
accelerator all the way down.
Notice:If your vehicle seems to accelerate slowly
or not shift gears when you go faster, and you
continue to drive your vehicle that way, you could
damage the transmission. Have your vehicle
serviced right away. You can drive in LOW (L) when
you are driving less than 35 mph (56 km/h) and
DRIVE (D) for higher speeds until then.
LOW (L):This position gives you access to gear
ranges. This provides more engine braking but lower
fuel economy than DRIVE (D). You can use it on
very steep hills, or in deep snow or mud.
Electronic Range Select Mode
Electronic Range Selector (ERS) mode allows you to
choose the top-gear limit of the vehicle’s transmission
and the vehicle’s speed while driving down hill or towing
a trailer.
To use this feature, do the following:
1. Move the shift lever to LOW (L).
2. Press the plus/minus
button located on the
shift lever, to increase
or decrease the
gear range available
based upon your
current driving
conditions and needs.
2-32

Tow/Haul Mode
Your vehicle may have a Tow/Haul mode.
The button to turn it on or
off is located on instrument
panel under the climate
controls.
Push the button to turn it on, push it again to deactivate
the system. You can use this feature to assist when
towing or hauling a heavy load.
When Tow/Haul is activated the Tow/Haul symbol will
come on the instrument panel cluster. SeeTow/Haul
ModeunderTowing a Trailer on page 4-30for
more information.
Automatic Engine Grade Braking
Automatic Engine Grade Braking assists when driving
on a downhill grade. It maintains the vehicle’s speed by
automatically implementing a shift schedule that uses
the engine and the transmission to slow the vehicle. This
reduces wear on the brakes system and increases
control of the vehicle. The system constantly monitors
the vehicle’s speed, acceleration, throttle position,
and whether the brake pedal is being pressed, and
determines when to keep the current vehicle speed or
to slow down. The system will then automatically
command downshifts that reduces the vehicle’s speed,
until the brake pedal is no longer being pressed.
This indicates the desired vehicle speed has been
reached.
While in the Electronic Range Select (ERS) mode,
grade braking is deactivated, allowing the driver to
select a range and limiting the highest gear available.
Grade braking is available for normal driving and in
Tow/Haul mode.
SeeAutomatic Transmission Operation on page 2-30.
2-34

Parking Brake
To set the parking brake,
push down the parking
brake pedal down
with your left foot.
If the ignition is on, the brake system warning light will
come on. SeeBrake System Warning Light on
page 3-47.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 with your right foot. Push down momentarily
on the parking brake pedal with your left foot until you
feel the pedal release, then 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 be on 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 4-30.
2-35

Shifting Into PARK (P)
{CAUTION:
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake rmly set. Your vehicle can
roll. If you have left the engine running, the
vehicle can move suddenly. You or others
could be injured. To be sure your 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 4-30.
1. Hold the brake pedal down with your right foot and
set the parking brake. SeeParking Brake on
page 2-35for more information.
2. Move the shift lever into PARK (P) by holding in the
button on the shift lever and pushing the shift lever
all the way toward the front of the vehicle.
3. Turn the ignition key to LOCK/OFF.
4. Remove the key and take it with you. If you can
leave your vehicle with the ignition key in your
hand, your vehicle is in PARK (P).
Leaving Your Vehicle With the Engine
Running
{CAUTION:
It can be dangerous to leave your vehicle with
the engine running. Your vehicle could move
suddenly if the shift lever is not fully in
PARK (P) with the parking brake rmly set.
And, if you leave the vehicle with the engine
running, it could overheat and even catch re.
You or others could be injured. Do not leave
your vehicle with the engine running.
If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P) and your
parking brake is rmly set before you leave it. After you
have moved the shift lever into PARK (P), hold the
regular brake pedal down. Then, see if you can move
the shift lever away from PARK (P) without rst pushing
the button.
If you can, it means that the shift lever was not fully
locked in PARK (P).
2-36

Running the Engine While Parked
It is better not to park with the engine running. But if you
ever have to, here are some things to know.
{CAUTION:
Idling the engine with the climate control
system off could allow dangerous exhaust into
your vehicle. See the earlier caution under
Engine Exhaust on page 2-38.
Also, idling in a closed-in place can let deadly
carbon monoxide (CO) into your vehicle even if
the climate control fan is at the highest setting.
One place this can happen is a garage.
Exhaust — with CO — can come in easily.
NEVER park in a garage with the engine
running.
Another closed-in place can be a blizzard. See
Winter Driving on page 4-17.
{CAUTION:
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake rmly set. Your vehicle can
roll. Do not leave your 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 your vehicle will not move, even when
you are on fairly level ground, always set the
parking brake and move the shift lever to
PARK (P).
Follow the proper steps to be sure your vehicle will not
move. SeeShifting Into PARK (P) on page 2-36.
If you are pulling a trailer, seeTowing a Trailer on
page 4-30.
2-39

When the System Does Not Seem to
Work Properly
The driver disables the system.
The parking brake pedal is depressed.
The ultrasonic sensors are not clean. Keep your
vehicle’s rear bumper free of mud, dirt, snow,
ice and slush. For cleaning instructions, see
Washing Your Vehicle on page 5-92.
A trailer was attached to your vehicle, or a bicycle
or an object was hanging out of your liftgate
during your last drive cycle, the red light may
illuminate in the rear display. Once the attached
object is removed, URPA will return to normal
operation.
A tow bar is attached to your vehicle.
The vehicle’s bumper is damaged. Take the vehicle
to your dealer/retailer to repair the system.
Other conditions may affect system performance,
such as vibrations from a jackhammer or the
compression of air brakes on a very large truck.
If the system is still disabled, after driving forward at
least 15 mph (25 km/h), take your vehicle to your
dealer/retailer.
Rear Vision Camera
Your vehicle may have a Rear Vision Camera system.
Read the entire section before using the system.
The rear vision camera system is designed to help the
driver when backing up. See “Rear Vision Camera”
in the Index of the navigation manual.
OnStar®System
OnStar uses several innovative technologies and live
advisors to provide you with a wide range of safety,
security, information, and convenience services. If your
airbags deploy, the system is designed to make an
automatic call to OnStar Emergency advisors who can
request emergency services be sent to your location.
If you lock your keys in the vehicle, call OnStar at
1-888-4-ONSTAR and they can send a signal to unlock
your doors. If you need roadside assistance, press
the OnStar button and they can contact Roadside
Service for you.
2-47