2021 GMC ACADIA ECU

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
204 Driving and Operating
{Warning
When driving off-road, bouncing and
quick changes in direction can easily
throw you out of position. This could
cause you to lose control and crash. You
and your passengers should always wear
seat belts.
Before Driving Off-Road
.Have all necessary maintenance and
service work completed.
.Fuel the vehicle, fill fluid levels, and check
inflation pressure in all tires, including the
spare, if equipped.
.Read all the information about AWD
vehicles in this manual.
.Make sure all underbody shields,
if equipped, are properly attached.
.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. 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 0209.
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 0219.
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 of control. Driving across hills
can cause a rollover. You could be injured
or killed. Do not drive on steep hills.
Before driving on a hill, assess the
steepness, traction, and obstructions. If the
terrain ahead cannot be seen, get out of the
vehicle and walk the hill before driving
further.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
212 Driving and Operating
Certification/Tire Label
Label Example
A vehicle-specific Certification/Tire label
is attached to the center pillar (B-pillar).
The label may show the size of the
vehicle's original tires and the inflation
pressures needed to obtain the gross
weight capacity of the vehicle. The label
shows the gross weight capacity of the
vehicle. This is called the Gross Vehicle
Weight Rating (GVWR). The GVWR
includes the weight of the vehicle, all
occupants, fuel, and cargo.The Certification/Tire label may also
show the maximum weights for the
front and rear axles, called the Gross
Axle Weight Rating (GAWR). To find out
the actual loads on the front and rear
axles, weigh the vehicle at a weigh
station. Your dealer can help with this.
Be sure to spread the load equally on
both sides of the centerline.
Caution
Overloading the vehicle may cause
damage. Repairs would not be covered by
the vehicle warranty. Do not overload the
vehicle.
{Warning
Things 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. In the cargo area, put
them as far forward as possible.
Try to spread the weight evenly.
(Continued)
Warning (Continued)
.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.
.Secure loose items in the vehicle.
.Do not leave a seat folded down
unless needed.
Starting and Operating
New Vehicle Break-In
Caution
The vehicle does not need an elaborate
break-in. But it will perform better in the
long run if you follow these guidelines:
.Do not drive at any one constant
speed, fast or slow, for the first
800 km (500 mi). Do not make
full-throttle starts. Avoid downshifting
to brake or slow the vehicle.
(Continued)

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
258 Driving and Operating
Before driving, inspect all trailer hitch parts
and attachments, safety chains, electrical
connectors, lamps, tires, and mirrors. See
Towing Equipment0262. If the trailer has
electric brakes, start the combination
moving and then manually apply the trailer
brake controller to check the trailer brakes
work. During the trip, occasionally check
that the cargo and trailer are secure and
that the lamps and any trailer brakes are
working.
Towing with a Stability Control System
When towing, the stability control system
might be heard. The system reacts to
vehicle movement caused by the trailer,
which mainly occurs during cornering. This is
normal when towing heavier trailers.
Following Distance
Stay at least twice as far behind the vehicle
ahead as you would when driving 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 of the
vehicle and trailer will not accelerate as
quickly and is much longer than the vehicle
alone. It is necessary to go much farther
beyond the passed vehicle before returning
to the lane. Pass on level roadways. Avoid
passing on hills if possible.
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 that hand to the
right. Always back up slowly and, if possible,
have someone guide you.
Making Turns
Caution
Turn more slowly and make wider arcs
when towing a trailer to prevent damage
to your vehicle. Making very sharp turns
could cause the trailer to contact the
vehicle. Make wider turns than normal when towing,
so the trailer will not go over soft shoulders,
over curbs, or strike road signs, trees,
or other objects. Always signal turns well in
advance. Do not steer or brake suddenly.
Driving on Grades
Reduce speed and shift to a lower gear
before starting down a long or steep
downhill grade. If the transmission is not
shifted down, the brakes may overheat and
result in reduced braking efficiency.
The vehicle can tow in D (Drive). Shift the
transmission to a lower gear if the
transmission shifts too often under heavy
loads and/or hilly conditions.
When towing at higher altitudes, engine
coolant will boil at a lower temperature
than at lower altitudes. If the engine is
turned off immediately after towing at high
altitude on steep uphill grades, the vehicle
could show signs similar to engine
overheating. To avoid this, let the engine
run, preferably on level ground, with the
transmission in P (Park) for a few minutes
before turning the engine off. If the
overheat warning comes on, see
Engine
Overheating 0285.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
280 Vehicle Care
When to Inspect the Engine Air Cleaner/
Filter
If the vehicle is not equipped with the
engine air filter life system, see
Maintenance Schedule0346 for intervals on
inspecting and replacing the engine air
cleaner/filter.
If equipped with the engine air filter life
system, see Engine Air Filter Life System
0 279.
How to Inspect/Replace the Engine Air
Cleaner/Filter
Do not start the engine or have the engine
running with the engine air cleaner/filter
housing open. Before removing the engine
air cleaner/filter, make sure that the engine
air cleaner/filter housing and nearby
components are free of dirt and debris. Do
not clean the engine air cleaner/filter or
components with water or compressed air. To inspect or replace the air cleaner/filter:2.0L L4 Engine
1. Remove the five screws and lift the cover out of the assembly.
{Warning
If part replacement is necessary, the part
must be replaced with one of the same
part number or with an equivalent part.
Use of a replacement part without the
same fit, form, and function may result
in personal injury or damage to the
vehicle.
2. Inspect or replace the engine air cleaner/ filter. 3. Lower the cover and secure with the five
screws.
4. If equipped, reset the engine air filter life system after replacing the engine air
filter. See Engine Air Filter Life System
0 279.2.5L L4 Engine
1. Remove the five screws and lift the cover out of the assembly.
2. Inspect or replace the engine air cleaner/ filter.
3. Lower the cover and secure with the five screws.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
Vehicle Care 281
4. If equipped, reset the engine air filter lifesystem after replacing the engine air
filter. See Engine Air Filter Life System
0 279.
3.6L V6 Engine
1. Remove the five screws and lift the cover out of the assembly.
2. Inspect or replace the engine air cleaner/ filter. 3. Lower the cover and secure with the five
screws.
4. If equipped, reset the engine air filter life system after replacing the engine air
filter. See Engine Air Filter Life System
0 279.
{Warning
Operating the engine with the air
cleaner/filter off can cause you or others
to be burned. Use caution when working
on the engine. Do not start the engine or
drive the vehicle with the air cleaner/
filter off, as flames may be present if the
engine backfires.
Caution
If the air cleaner/filter is off, dirt can
easily get into the engine, which could
damage it. Always have the air cleaner/
filter in place when driving.
Cooling System
The cooling system allows the engine to
maintain the correct working temperature.
2.0L L4 Engine
1. Engine Cooling Fan (Out of View)
2. Engine Coolant Surge Tank and
Pressure Cap

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
Vehicle Care 285
6. Verify coolant level after the engine isshut off and the coolant is cold.
If necessary, repeat coolant fill procedure
Steps 1–6.
If the coolant still is not at the proper
level when the system cools down again,
see your dealer.
Caution
If the pressure cap is not tightly installed,
coolant loss and engine damage may
occur. Be sure the cap is properly and
tightly secured.
Automatic Coolant Service Fill (2.0L
Engine Only)
If equipped, this feature assists in filling and
removing air from the cooling system after
service of components or when coolant is
added after being too low.
To activate the fill and air removal process:
1. With a cold system, disconnect the vent line from the port near the cap on the
surge tank. Add coolant to the indicated
mark on the surge tank.
2. Reconnect the vent line to the surge tank and replace the cap on the
surge tank. 3. Connect the vehicle to a battery charger.
4. Put the vehicle in Service Mode. See
Ignition Positions 0213.
5. Turn off the air conditioning.
6. Set the parking brake.
7. At the same time, press the accelerator and the brake for automatic transmission
vehicles for two seconds, then release.
At the end of the cycle, check the coolant
level in the surge tank and add coolant, if it
is low. Turn off the vehicle, allow the Engine
Control Module (ECM) to go to sleep, about
two minutes, and repeat steps 3-7.
Listen for pump activation and movement of
the control valves while watching the level
of the tank. If the tank empties, turn the
ignition off, carefully remove the surge tank
cap, refill to the indicated mark and repeat
steps 3-6. The fill and air removal process
will run for approximately 10 minutes.
Engine Overheating
The vehicle has several indicators to warn of
the engine overheating. There is an engine coolant temperature
gauge on the instrument cluster. See
Engine
Coolant Temperature Gauge 0104. The
vehicle may also display a message on 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
0 366.
If the decision is made to lift the hood,
make sure the vehicle is parked on a level
surface. Then check to see if the engine
cooling fan is running. If the engine is
overheating, the fan should be running. If it
is not, do not continue to run the engine.
Have the vehicle serviced.
Caution
Do 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.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
290 Vehicle Care
Wiper Blade Replacement
Windshield wiper blades should be inspected
for wear or cracking.
It is a good idea to clean or replace the
wiper blade assembly on a regular basis or
when worn. For proper windshield wiper
blade length and type, seeMaintenance
Replacement Parts 0355.
Caution
Allowing the wiper 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 arm to touch the
windshield.
Front Wiper Blade Replacement
To replace the wiper blade assembly:
1. Pull the windshield wiper assembly away from the windshield.
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.
5. Reverse Steps 1–3 for wiper blade replacement.
Rear Wiper Blade Replacement
To remove the wiper blade:
1. Lift the wiper arm away from the window. The rear wiper arm will only lift
off the glass at a small angle to allow for wiper blade removal. The rear wiper
arm will not lock in a service up position
so care should be taken when replacing
the rear wiper blade.
2. Push the release lever to disengage the
hook and push the wiper arm toward the
center of the vehicle and out of the
blade assembly.
3. Push the new blade assembly securely on the wiper arm until the release lever
clicks into place.
Windshield Replacement
Driver Assistance Systems
If the windshield needs to be replaced and
the vehicle is equipped with a front camera
sensor for the Driver Assistance Systems, a
GM replacement windshield is
recommended. The replacement windshield
must be installed according to GM
specifications for proper alignment. If it is
not, these systems may not work properly,

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
Vehicle Care 319
Warning (Continued)
or remove the traction device if it
contacts the vehicle. Do not spin the
wheels. If traction devices are used,
install them on the front tires.
Caution
If the vehicle is equipped with a tire size
other than 235/55R20, 245/65R17,
or 255/65R17 use tire chains only where
legal and only when necessary. Use low
profile chains that add no more than
12 mm thickness to the tire tread and
inner sidewall. Use chains that are the
proper size for the tires. Install them on
the tires of the front axle. Do not use
chains on the tires of the rear axle.
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.
If a Tire Goes Flat
It is unusual for a tire to blow out while
driving, especially if the tires are maintained
properly. SeeTires0300. If air goes out of
a tire, it is much more likely to leak out
slowly. But if there is ever a blowout, here
are a few tips about what to expect and
what to do:
If a front tire fails, the flat tire creates a
drag that pulls the vehicle toward that side.
Take your foot off the accelerator pedal and
grip the steering wheel firmly. Steer to
maintain lane position, and then gently
brake to a stop, well off the road,
if possible.
A rear blowout, particularly on a curve, acts
much like a skid and may require the same
correction as used in a skid. Stop pressing
the accelerator pedal and steer to straighten
the vehicle. It may be very bumpy and
noisy. Gently brake to a stop, well off the
road, if possible.
{Warning
Driving on a flat tire will cause
permanent damage to the tire.
Re-inflating a tire after it has been driven
(Continued)
Warning (Continued)
on while severely underinflated or flat
may cause a blowout and a serious crash.
Never attempt to re-inflate a tire that has
been driven on while severely
underinflated or flat. Have your dealer or
an authorized tire service center repair or
replace the flat tire as soon as possible.
{Warning
Lifting a vehicle and getting under it to
do maintenance or repairs is dangerous
without the appropriate safety equipment
and training. If a jack is provided with
the vehicle, it is designed only for
changing a flat tire. If it is used for
anything else, you or others could be
badly injured or killed if the vehicle slips
off the jack. If a jack is provided with the
vehicle, only use it for changing a
flat tire.
If a tire goes flat, avoid further tire and
wheel damage by driving slowly to a level
place, well off the road, if possible. Turn on
the hazard warning flashers. See Hazard
Warning Flashers 0134.