2021 GMC TERRAIN wiring

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
56 Seats and Restraints
Adding Equipment to the
Airbag-Equipped Vehicle
Adding accessories that change the vehicle's
frame, bumper system, height, front end,
or side sheet metal may keep the airbag
system from working properly.
The operation of the airbag system can also
be affected by changing, including
improperly repairing or replacing, any parts
of the following:
.Airbag system, including airbag modules,
front or side impact sensors, sensing and
diagnostic module, or airbag wiring
.Front seats, including stitching, seams or
zippers
.Seat belts
.Steering wheel, instrument panel,
overhead console, ceiling trim, or pillar
garnish trim
.Inner door seals, including speakers
Your dealer and the service manual have
information about the location of the airbag
modules and sensors, sensing and diagnostic
module, and airbag wiring along with the
proper replacement procedures. In addition, the vehicle has a passenger
sensing system for the front outboard
passenger position, which includes sensors
that are part of the passenger seat. The
passenger sensing system may not operate
properly if the original seat trim is replaced
with non-GM covers, upholstery, or trim; or
with GM covers, upholstery, or trim
designed for a different vehicle. Any object,
such as an aftermarket seat heater or a
comfort-enhancing pad or device, installed
under or on top of the seat fabric, could
also interfere with the operation of the
passenger sensing system. This could either
prevent proper deployment of the passenger
airbag(s) or prevent the passenger sensing
system from properly turning off the
passenger airbag(s). See
Passenger Sensing
System 052.
If the vehicle has rollover roof-rail airbags,
see Different Size Tires and Wheels 0301 for
additional important information.
If the vehicle must be modified because you
have a disability and have questions about
whether the modifications will affect the
vehicle's airbag system, or if you have
questions about whether the airbag system will be affected if the vehicle is modified for
any other reason, call Customer Assistance.
See
Customer Assistance Offices 0348.
Airbag System Check
The airbag system does not need regularly
scheduled maintenance or replacement.
Make sure the airbag readiness light is
working. See Airbag Readiness Light 092.
Caution
If an airbag covering is damaged, opened,
or broken, the airbag may not work
properly. Do not open or break the airbag
coverings. If there are any opened or
broken airbag coverings, have the airbag
covering and/or airbag module replaced.
For the location of the airbags, see Where
Are the Airbags? 048. See your dealer
for service.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
92 Instruments and Controls
When the vehicle is started, this light
flashes and a chime may come on to remind
passengers to fasten their seat belt.
Then the light stays on solid until the belt is
buckled. This cycle continues several times if
the front passenger remains or becomes
unbuckled while the vehicle is moving.
If the front passenger seat belt is buckled,
neither the chime nor the light comes on.
The front passenger seat belt reminder light
and chime may come on if an object is put
on the seat such as a briefcase, handbag,
grocery bag, laptop, or other electronic
device. To turn off the reminder light and/or
chime, remove the object from the seat or
buckle the seat belt.
Airbag Readiness Light
This light shows if there is an electrical
problem with the airbag system. It is
located in the instrument cluster. The
system check includes the airbag sensor(s),the passenger sensing system, the
pretensioners, the airbag modules, the
wiring, and the crash sensing and diagnostic
module. For more information on the airbag
system, see
Airbag System 047.
The airbag readiness light comes on for
several seconds when the vehicle is started.
If the light does not come on then, have it
fixed immediately.
{Warning
If the airbag readiness light stays on
after the vehicle is started or comes on
while driving, it means the airbag system
might not be working properly. The
airbags in the vehicle might not inflate in
a crash, or they could even inflate
without a crash. To help avoid injury,
have the vehicle serviced right away. If there is a problem with the airbag
system, a Driver Information Center (DIC)
message may also come on.
Passenger Airbag Status Indicator
The vehicle has a passenger sensing system.
See
Passenger Sensing System 052 for
important safety information. The overhead
console has a passenger airbag status
indicator.
When the vehicle is started, the passenger
airbag status indicator will light ON and OFF,
and the symbols for on and off, for several
seconds as a system check. Then, after
several more seconds, the status indicator
will light either ON or OFF, and either the
on or off symbol, to let you know the
status of the front outboard passenger
frontal airbag.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
266 Vehicle Care
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.
1. Screws
2. Air Duct Clamp
3. Electrical Connector
To inspect or replace the engine air cleaner/
filter:1. Open the hood. See Hood0259.
2. Loosen the screw on the air duct clamp (2) and remove the air duct hose
from the cover.
3. Remove the four screws (1) and remove the air cleaner/filter cover, keeping the
wiring harness electrical connector (3)
connected to the sensor.
4. Pull straight up on the cover, and while holding the cover, remove the air
cleaner/filter.
{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.
5. Inspect or replace the air cleaner/filter.
How to Reinstall the Engine Air Cleaner/
Filter
1. Align the air cleaner/filter with the indicated point on the base of the air
cleaner/filter housing and install the air
cleaner/filter. The outer air cleaner/filter
seal must be fitted properly in the air
cleaner/filter housing.
2. Align the air cleaner/filter housing cover tabs to the air cleaner/filter housing.
3. Install the air cleaner/filter housing cover using the four screws.
4. Slide the air duct onto the cover assembly and tighten the screw on the
air duct clamp.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
Vehicle Care 267
5. Verify that the wiring harness connectoris fully connected to the sensor on the
air cleaner/filter housing.
6. If equipped, reset the engine air filter life system after replacing the engine air
filter, see Engine Air Filter Life System
0 265.
{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
1. Engine Cooling Fan (Out of View)
2. Engine Coolant Surge Tank and
Pressure Cap
{Warning
An underhood electric fan can start up
even when the engine is not running and
can cause injury. Keep hands, clothing,
and tools away from any underhood
electric fan.
{Warning
Do not touch heater or radiator hoses,
or other engine parts. They can be very
hot and can burn you. Do not run the
engine if there is a leak; all coolant could
leak out. That could cause an engine fire
and can burn you. Fix any leak before
driving the vehicle.
If the coolant inside the coolant surge tank
is boiling, do not do anything else until it
cools down. The vehicle should be parked on
a level surface.
The coolant level should be at the top rib on
the middle of the tank. If it is not, the
vehicle may have a leak at the radiator
hoses, heater hoses, radiator, water pump,
or somewhere else in the cooling system.
If there seems to be no leak, with the
engine on, check to see if the electric engine
cooling fan is running. If the engine is
overheating, the fan should be running. If it
is not, the vehicle needs service. Turn off
the engine.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
278 Vehicle Care
LED Lighting
This vehicle has several LED lamps. For
replacement of any LED lighting assembly,
contact your dealer.
Front Turn Signal Lamps
To replace one of these bulbs:1. Open the hood. See Hood0259.
2. Remove the bulb access cap from the top
of the headlamp assembly by turning it
counterclockwise.
3. Remove the bulb from the bulb socketby pinching the tabs on either side of
the bulb and pull straight out.
4. Install the new bulb in the bulb socket.
5. Install the bulb access cap onto the headlamp assembly by turning clockwise.
Taillamps
To replace one of these lamps:
1. Open the liftgate. See Liftgate017.
2. Remove the two screw caps and two
screws from the taillamp assembly.
3. Pull the taillamp assembly out of the vehicle body.
4. Disconnect the lamp wiring harness.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
280 Vehicle Care
Electrical System
Electrical System Overload
The vehicle has fuses and circuit breakers to
protect against an electrical system
overload.
When the electrical load current is too
heavy, the circuit breaker opens and closes,
protecting the circuit until the current load
returns to normal or the problem is fixed.
This greatly reduces the chance of circuit
overload and fire caused by electrical
problems.
Replace a bad fuse with a new one of the
identical size and rating.
If there is a problem on the road and a fuse
needs to be replaced, the same amperage
fuse can be borrowed. Choose some feature
of the vehicle that is not needed to use and
replace it as soon as possible.
Headlamp Wiring
An electrical overload may cause the lamps
to go on and off, or in some cases to
remain off. Have the headlamp wiring
checked right away if the lamps go on and
off or remain off.
Windshield Wipers
If the wiper motor overheats due to heavy
snow or ice, the windshield wipers will stop
until the motor cools and will then restart.
Although the circuit is protected from
electrical overload, overload due to heavy
snow or ice may cause wiper linkage
damage. Always clear ice and heavy snow
from the windshield before using the
windshield wipers.
If the overload is caused by an electrical
problem and not snow or ice, be sure to get
it fixed.
Fuses and Circuit Breakers
The wiring circuits in the vehicle are
protected from short circuits by a
combination of fuses and circuit breakers.
This greatly reduces the chance of damage
caused by electrical problems.
{Danger
Fuses and circuit breakers are marked
with their ampere rating. Do not exceed
the specified amperage rating when
replacing fuses and circuit breakers. Use
of an oversized fuse or circuit breaker can
result in a vehicle fire. You and others
could be seriously injured or killed.