2012 GMC ACADIA brake light

Black plate (28,1)GMC Acadia/Acadia Denali Owner Manual - 2012
9-28 Driving and Operating
If driving safely on a wet road and it
becomes necessary to slam on the
brakes and continue braking to
avoid a sudden obstacle, a
computer senses that the wheels
are slowing down. If one of the
wheels is about to stop rolling, the
computer will separately work the
brakes at each wheel.
ABS can change the brake pressure
to each wheel, as required, faster
than any driver could. This can help
the driver steer around the obstacle
while braking hard.
As the brakes are applied, the
computer keeps receiving updates
on wheel speed and controls
braking pressure accordingly.
Remember: ABS does not change
the time needed to get a foot up to
the brake pedal or always decrease
stopping distance. If you get too
close to the vehicle in front of you,there will not be enough time to
apply the brakes if that vehicle
suddenly slows or stops. Always
leave enough room up ahead to
stop, even with ABS.
Using ABS
Do not pump the brakes. Just hold
the brake pedal down firmly and let
ABS work. You might hear the ABS
pump or motor operating and feel
the brake pedal pulsate, but this is
normal.
Braking in Emergencies
ABS allows the driver to steer and
brake at the same time. In many
emergencies, steering can help
more than even the very best
braking.
Parking Brake
To set the parking brake, hold the
regular brake pedal down, then
push the parking brake pedal down.
If the ignition is on, the brake
system warning light will come on.
See
Brake System Warning Light on
page 5‑21.

Black plate (29,1)GMC Acadia/Acadia Denali Owner Manual - 2012
Driving and Operating 9-29
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 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 Driving
Characteristics and Towing Tips on
page 9‑45.Brake Assist
This vehicle has a brake assist
feature designed to assist the
driver in stopping or decreasing
vehicle speed in emergency driving
conditions. This feature uses the
stability system hydraulic brake
control module to supplement
the power brake system under
conditions where the driver has
quickly and forcefully applied the
brake pedal in an attempt to quickly
stop or slow down the vehicle.
The stability system hydraulic brake
control module increases brake
pressure at each corner of the
vehicle until the ABS activates.
Minor brake pedal pulsation or
pedal movement during this time
is normal and the driver should
continue to apply the brake pedal
as the driving situation dictates.
The brake assist feature will
automatically disengage when
the brake pedal is released or
brake pedal pressure is quickly
decreased.
Hill Start Assist (HSA)
This vehicle has a Hill Start Assist
(HSA) feature, which may be useful
when the vehicle is stopped on a
grade. This feature is designed to
prevent the vehicle from rolling,
either forward or rearward, during
vehicle drive off. After the driver
completely stops and holds the
vehicle in a complete standstill on a
grade, HSA will be automatically
activated. During the transition
period between when the driver
releases the brake pedal and starts
to accelerate to drive off on a grade,
HSA holds the braking pressure
to ensure that there is no rolling.
The brakes will automatically
release when the accelerator pedal
is applied within the two‐second
window. It will not activate if the
vehicle is in a drive gear and facing
downhill or if the vehicle is facing
uphill and in R (Reverse).

Black plate (30,1)GMC Acadia/Acadia Denali Owner Manual - 2012
9-30 Driving and Operating
Ride Control Systems
StabiliTrak®System
The vehicle has the StabiliTrak
system which combines antilock
brake, traction, and stability control
systems and helps the driver
maintain directional control of the
vehicle in most driving conditions.
When you first start the vehicle and
begin to drive away, the system
performs several diagnostic checks
to ensure there are no problems.
The system may be heard or felt
while it is working. This is normal
and does not mean there is a
problem with the vehicle. The
system should initialize before the
vehicle reaches 32 km/h (20 mph).
In some cases, it may take
approximately 3.2 km (2 mi) of
driving before the system initializes.
If the system fails to turn on or
activate, one of the following
messages will be displayed on theDriver Information Center (DIC):
SERVICE TRACTION CONTROL,
SERVICE STABILITRAK, the
StabiliTrak light will come on and
stay and four chimes are heard.
If these conditions are observed,
turn the vehicle off, wait
15 seconds, and then turn it back
on again to reset the system. If any
of these messages still appear on
the Driver Information Center (DIC),
the vehicle should be taken in for
service. For more information on the
DIC messages, see
Ride Control
System Messages on page 5‑42.
The StabiliTrak light will flash on the
instrument panel cluster when the
system is both on and activated.
The system may be heard or felt
while it is working; this is normal.
The traction control button is
located on the instrument panel.
The traction control part of
StabiliTrak can be turned off by
pressing and releasing the traction
control button.
Traction control can be turned on by
pressing and releasing the traction
control button and the appropriate
TRACTION CONTROL ON
message will be displayed, if not
automatically shut off for any other
reason.
When the traction control system
is turned off, the appropriate
TRACTION CONTROL OFF
message will be displayed on the
DIC. The vehicle will still have
brake-traction control when traction
control is off, but will not be able to
use the engine speed management

Black plate (31,1)GMC Acadia/Acadia Denali Owner Manual - 2012
Driving and Operating 9-31
system. See“Traction Control
Operation” following for more
information.
When the traction control system
has been turned off, system noises
may be heard and felt as a result of
the brake-traction control working.
It is recommended to leave the
system on for normal driving
conditions, but it may be necessary
to turn the system off if the vehicle
is stuck in sand, mud, ice, or snow,
and you want to “rock”the vehicle to
attempt to free it. It may also be
necessary to turn off the system
when driving in extreme off-road
conditions where high wheel spin is
required. See If the Vehicle Is Stuck
on page 9‑10.
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 the brakes as necessary. The traction control system is
enabled automatically when the
vehicle is started. It will activate and
the StabiliTrak light will flash if it
senses that any of the wheels are
spinning or beginning to lose
traction while driving. If traction
control is turned off, 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 the wheel(s) of one axle
is allowed to spin excessively
while the StabiliTrak
®, ABS, brake
warning lights, and any relevant
DIC messages are displayed, the
transfer case could be damaged.
The repairs would not be covered
by the vehicle warranty. Reduce
engine power and do not spin the wheel(s) excessively while
these lights and messages 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,
a reduction in acceleration may be
noticed, or a noise or vibration may
be heard. This is normal.
If cruise control is being used when
the system activates, the StabiliTrak
light will flash and cruise control will
automatically disengage. Cruise
control may be reengaged when
road conditions allow. See
Cruise
Control on page 9‑32.
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, see your
dealer for service.

Black plate (32,1)GMC Acadia/Acadia Denali Owner Manual - 2012
9-32 Driving and Operating
Cruise Control
With cruise control, a speed of
about 40 km/h (25 mph) or more can
be maintained without keeping your
foot on the accelerator. Cruise
control does not work at speeds
below about 40 km/h (25 mph).
When the brakes are applied, the
cruise control is disengaged.
{WARNING
Cruise control can be dangerous
where you cannot drive safely at
a steady speed. So, do not use
the cruise control on winding
roads or in heavy traffic.
Cruise control can be dangerous
on slippery roads. On such roads,
fast changes in tire traction can
cause excessive wheel slip, and
you could lose control. Do not use
cruise control on slippery roads.The cruise control buttons are
located on left side of the steering
wheel.
T(On/Off):Press to turn cruise
control on and off. The indicator
comes on when cruise control is on.
+ RES (Resume/Accelerate):
Press briefly to make the vehicle
resume to a previously set speed,
or press and hold to accelerate.
SET–: Press to set the speed and
activate cruise control or to make
the vehicle decelerate.
[(Cancel): Press to disengage
cruise control without erasing the
set speed from memory.
Setting Cruise Control
If the cruise button is on when not in
use, it could get bumped and go into
cruise when not desired. Keep the
cruise control switch off when cruise
is not being used.
The cruise control light on the
instrument panel cluster comes on
after the cruise control has been set
to the desired speed.
1. Press the
Ibutton to turn the
cruise control system on.
2. Get up to the speed desired.
3. Press and release the SET– button located on the steering
wheel.
4. Take your foot off the accelerator.

Black plate (33,1)GMC Acadia/Acadia Denali Owner Manual - 2012
Driving and Operating 9-33
Resuming a Set Speed
If the cruise control is set at a
desired speed and then the brakes
are applied, the cruise control is
disengaged without erasing the set
speed from memory.
Once the vehicle speed is 40 km/h
(25 mph) or greater, press the
+RES button on the steering wheel.
The vehicle returns to the previously
set speed and stays there.
Increasing Speed While Using
Cruise Control
If the cruise control system is
already activated:
.Press and hold the +RES button
on the steering wheel until the
desired speed is reached, then
release it.
.To increase vehicle speed in
small increments, press the
+RES button briefly. Each time
this is done, the vehicle goes
about 1.6 km/h (1 mph) faster.Reducing Speed While Using
Cruise Control
If the cruise control system is
already activated:
.Press and hold the SET–
button
on the steering wheel until the
lower speed desired is reached,
then release it.
.To slow down in small amounts,
press the SET– button briefly.
Each time this is done, the
vehicle goes about 1.6 km/h
(1 mph) slower.
Passing Another Vehicle While
Using Cruise Control
Use the accelerator pedal to
increase vehicle speed. When you
take your foot off the pedal, the
vehicle will slow down to the
previously set cruise speed.
Using Cruise Control on Hills
How well the cruise control will work
on hills depends upon the vehicle
speed, load, and the steepness of the hills. When going up steep hills,
you might have to step on the
accelerator pedal to maintain the
vehicle speed. When going
downhill, you might have to brake
or shift to a lower gear to keep the
vehicle speed down. When the
brakes are applied the cruise control
is disengaged.
Ending Cruise Control
There are three ways to end cruise
control:
.Step lightly on the brake pedal.
.Press the[button.
.To turn off the cruise control,
press
Ton the steering wheel.
Erasing Speed Memory
The cruise control set speed is
erased from memory by pressing
Tor if the ignition is turned off.

Black plate (52,1)GMC Acadia/Acadia Denali Owner Manual - 2012
9-52 Driving and Operating
Weight-Distributing Hitches and
Weight Carrying Hitches
A. Body-to-Ground Distance
B. Front of Vehicle
When using a weight-distributing
hitch, the hitch must be adjusted so
that the distance (A) remains the
same both before and after coupling
the trailer to the tow vehicle.
Safety Chains
Always attach chains between the
vehicle and the trailer. Cross the
safety chains under the tongue
of the trailer to help prevent the
tongue from contacting the road if it
becomes separated from the hitch.
Always leave just enough slack so
the rig can turn. Never allow safety
chains to drag on the ground.
Trailer Brakes
A loaded trailer that weighs more
than 450 kg (1,000 lbs) needs to
have its own brake system that is
adequate for the weight of the
trailer. Be sure to read and follow
the instructions for the trailer brakes
so they are installed, adjusted, and
maintained properly.
Because the vehicle has antilock
brakes, do not try to tap into the
vehicle's hydraulic brake system.
If you do, both brake systems will
not work well, or at all.
Trailer Wiring Harness
Basic Trailer Wiring
The trailer wiring harness, with a
seven-pin connector, is located at
the rear of the vehicle and is tied to
the vehicle's frame. The harness
connector can be plugged into a
seven-pin universal heavy-duty
trailer connector available through
your dealer.
The seven-wire harness contains
the following trailer circuits:
.Yellow: Left Stop/Turn Signal
.Dark Green: Right Stop/Turn
Signal
.Brown: Taillamps
.Black: Ground
.Light Green: Back-up Lamps
.Red/Black: Battery Feed
.Dark Blue: Trailer Brake*

Black plate (53,1)GMC Acadia/Acadia Denali Owner Manual - 2012
Driving and Operating 9-53
*The fuse for this circuit is installed
in the underhood electrical center,
but the wires are not connected.
They should be connected by your
dealer or a qualified service center.
If the back-up lamp circuit is not
functional, contact your dealer.
If a remote (non-vehicle) battery is
being charged, press the Tow/Haul
mode switch located on the center
console near the climate controls.
This will boost the vehicle system
voltage and properly charge the
battery. If the trailer is too light for
Tow/Haul mode, turn on the
headlamps (non‐HID only) as a
second way to boost the vehicle
system and charge the battery.Electric Trailer Brake Control
Wiring Provisions
These wiring provisions for an
electric trailer brake controller are
included with the vehicle as part
of the trailer wiring package.
The instrument panel contains
blunt cut wires behind the steering
column for the electric trailer brake
controller. The harness contains the
following wires:
.Red/Black: Power Supply
.White: Brake Switch Signal
.Gray: Illumination
.Dark Blue: Trailer Brake Signal
.Black: Ground
The electric trailer brake controller
should be installed by your dealer or
a qualified service center.
Conversions and
Add-Ons
Add-On Electrical
Equipment
Notice: Do not add anything
electrical to the vehicle unless
you check with your dealer first.
Some electrical equipment can
damage the vehicle and the
damage would not be covered
by the vehicle's warranty. Some
add-on electrical equipment can
keep other components from
working as they should.
Add-on equipment can drain the
vehicle's 12‐volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle on page 3‑35 andAdding
Equipment to the Airbag-Equipped
Vehicle on page 3‑36.