2018 GMC SIERRA trailer

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Driving and Operating 335
If TSC is enabled, the Traction
Control System (TCS)/StabiliTrak
warning light will flash on the
instrument cluster. Vehicle speed
must be reduced. If trailer sway
continues, StabiliTrak can reduce
engine torque to help slow the
vehicle. SeeTraction Control/
Electronic Stability Control 0282.
{Warning
Even if the vehicle is equipped
with TSC, trailer sway could result
in loss of control and the vehicle
could crash. If excessive trailer
sway is detected, slow down to a
safe speed. Check the trailer and
vehicle to help correct possible
causes. These could include an
improperly or overloaded trailer,
unrestrained cargo, improper
trailer hitch configuration,
excessive vehicle-trailer speed,
or improperly inflated or incorrect
vehicle or trailer tires. See Towing
Equipment 0325 for trailer
ratings and hitch setup
recommendations. Adding non-dealer accessories can
affect the vehicle performance. See
Accessories and Modifications
0
343.
Electronic Trailer Sway Control
Devices
Some trailers may come equipped
with an electronic device designed
to reduce or control trailer sway.
Aftermarket equipment
manufacturers also offer similar
devices that connect to the wiring
between the trailer and the vehicle.
These devices may interfere with
the vehicle’ s trailer brake or other
systems, including integrated
anti-sway systems, if equipped.
Messages related to trailer
connections or trailer brakes could
appear on the Driver Information
Center (DIC). The effect that these
devices may have on vehicle
handling or trailer brake
performance is unknown.
{Warning
Use of electronic trailer sway
control devices could result in
reduced trailer brake
performance, loss of trailer
brakes, or other malfunctions, and
could cause a crash. You or
others could be injured or killed.
Before using one of these
devices:
. Ask the device or trailer
manufacturer if the device
has been thoroughly tested
for compatibility with the
make, model, and year of
the vehicle as well as
optional equipment installed
on the vehicle.
. Before driving on the open
roads, check that the trailer
brakes are working properly.
Drive the vehicle with the
trailer attached on a level
road surface that is free of
traffic at about 32-40 km/h
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
336 Driving and Operating
Warning (Continued)
(20-25 mph) and fully apply
the manual trailer brake
apply lever. Also check that
the trailer brake lamps and
other lamps are functioning
correctly.
. If the trailer brakes are not
operating properly at any
time, or if a DIC message
indicates problems with the
trailer connections or trailer
brakes, carefully pull the
vehicle over to the side of
the road when traffic
conditions allow.
Conversions and
Add-Ons
Add-On Electrical
Equipment
{Warning
The Data Link Connector (DLC) is
used for vehicle service
and Emission Inspection/
Maintenance testing. See
Malfunction Indicator Lamp
(Check Engine Light) 0150.
A device connected to the DLC —
such as an aftermarket fleet or
driver-behavior tracking device —
may interfere with vehicle
systems. This could affect vehicle
operation and cause a crash.
Such devices may also access
information stored in the vehicle’s
systems.
Caution
Some electrical equipment can
damage the vehicle or cause
components to not work and
would not be covered by the
vehicle warranty. Always check
with your dealer before adding
electrical equipment.
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 090 and Adding Equipment
to the Airbag-Equipped Vehicle
0 90.
For information on wiring auxiliary
switches, see www.gmupfitter.com
or contact your dealer.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
364 Vehicle Care
If there is an engine overheat
warning, but no steam is seen or
heard, the problem may not be too
serious. Sometimes the engine can
get a little too hot when the vehicle:
.Climbs a long hill on a hot day.
. Stops after high-speed driving.
. Idles for long periods in traffic.
. Tows a trailer; see Trailer Towing
0 307.
If the ENGINE OVERHEATED
STOP ENGINE or the ENGINE
OVERHEATED IDLE ENGINE
message appears with no sign of
steam, try this for a minute or so: 1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and to the
highest fan speed. Open the
windows as necessary.
3. When it is safe to do so, pull off the road, shift to P (Park) or
N (Neutral) and let the
engine idle. If the temperature overheat gauge is
no longer in the overheat zone or an
overheat warning no longer
displays, the vehicle can be driven.
Continue to drive the vehicle slowly
for about 10 minutes. Keep a safe
vehicle distance from the vehicle in
front. If the warning does not come
back on, continue to drive normally
and have the cooling system
checked for proper fill and function.
If the warning continues, pull over,
stop, and park the vehicle
right away.
If there is still no sign of steam and
the vehicle is equipped with an
engine driven cooling fan, push
down the accelerator until the
engine speed is about twice as fast
as normal idle speed for at least
five minutes while the vehicle is
parked. If the warning is still there,
turn off the engine and get everyone
out of the vehicle until it cools down.
If there is no sign of steam, idle the
engine for five minutes while
parked. If the warning is still
displayed, turn off the engine until it
cools down.Overheated Engine
Protection
Operating Mode
If an overheated engine condition
exists and the ENGINE POWER IS
REDUCED message displays, an
overheat protection mode which
alternates firing groups of cylinders
helps to prevent engine damage. In
this mode, a loss in power and
engine performance will be noticed.
This operating mode allows the
vehicle to be driven to a safe place
in an emergency. Driving extended
distances and/or towing a trailer in
the overheat protection mode
should be avoided.
Caution
After driving in the overheated
engine protection operating
mode, the engine oil will be
severely degraded. Any repairs
performed before the engine is
cool may cause engine damage.
Allow the engine to cool before
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 365
Caution (Continued)
attempting any repair. Repair the
cause of coolant loss, change the
oil, and reset the oil life system.
SeeEngine Oil 0350.
Engine Fan
If the vehicle has a clutched engine
cooling fan, when the clutch is
engaged, the fan spins faster to
provide more air to cool the engine.
In most everyday driving conditions,
the fan is spinning slower and the
clutch is not fully engaged. This
improves fuel economy and reduces
fan noise. Under heavy vehicle
loading, trailer towing, and/or high
outside temperatures, the fan speed
increases as the clutch more fully
engages, so an increase in fan
noise may be heard. This is normal
and should not be mistaken as the
transmission slipping or making
extra shifts. It is merely the cooling
system functioning properly. The fan will slow down when additional
cooling is not required and the
clutch disengages.
This fan noise may also be heard
when starting the engine. It will go
away as the fan clutch partially
disengages.
If the vehicle has electric cooling
fan(s), the fans may be heard
spinning at low speed during most
everyday driving. The fans may turn
off if no cooling is required. Under
heavy vehicle loading, trailer towing,
high outside temperatures,
or operation of the air conditioning
system, the fans may change to
high speed and an increase in fan
noise may be heard. This is normal
and indicates that the cooling
system is functioning properly. The
fans will change to low speed when
additional cooling is no longer
required.
The electric engine cooling fans
may run after the engine has been
turned. off. This is normal and no
service is required.
Power Steering Fluid
(1500 Series)
The vehicle has electric power
steering and does not use power
steering fluid.
Power Steering Fluid
(2500/3500 Series)
See
Engine Compartment Overview
0 345 for reservoir location.
When to Check Power Steering
Fluid
It is not necessary to regularly
check power steering fluid unless
there is a leak suspected in the
system or an unusual noise is
heard. A fluid loss in this system
could indicate a problem. Have the
system inspected and repaired.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
382 Vehicle Care
Lift the cover to access the fuse
block.
Caution
Spilling liquid on any electrical
component on the vehicle may
damage it. Always keep the
covers on any electrical
component.
A fuse puller is available in the left
instrument panel fuse block.
The vehicle may not be equipped
with all of the fuses, relays, and
features shown.
Fuses Usage
1 Trailer brake Fuses
Usage
2 Trailer battery

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 383
FusesUsage
3 Antilock brake system pump
4 Instrument panel BEC 1
5 Passenger motorized seat belt
6 4WD transfer case electronic control
7 Electric park brake
8 Instrument panel BEC 2
9 Driver motorized seat belt
10 Rear window defogger
11 Starter
12 Cooling fan 1
13 Cooling fan 2
14 Left trailer stop/ Turn signal lamps
15 Trailer parking lamps Fuses
Usage
16 Trailer reverse lamps
17 Right trailer stop/ Turn signal lamps
18 Fuel pump
19 Integrated chassis control module
20 Electronic suspension control
module
21 Fuel pump power module
22 Upfitter 1
23 Upfitter 2
24 Front wiper
25 Antilock brake system valve
26 Upfitter 2
27 Upfitter 3
28 Right parking lamps
29 Left parking lamps Fuses
Usage
30 Upfitter 3
31 Upfitter 4
32 Upfitter 4
33 Reverse lamps
34 Engine control module/Ignition
35 Air conditioning clutch
36 Heated mirrors
37 Upfitter 1
38 Center high-mounted
stoplamp
39 Miscellaneous/ Ignition
40 Transmission/ Ignition
41 Fuel pump 2
42 Cooling fan clutch
43 Engine
44 Fuel injectors A–odd

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
384 Vehicle Care
FusesUsage
45 Fuel injectors B–even
46 O2 Sensor B
47 Throttle control
48 Horn
49 Fog lamps
50 O2 Sensor A
51 Engine control module
52 Interior heater
53 Accessory power module/TPM pump
54 Front washer
55 Air conditioning/ Battery regulated
voltage control
56 Air conditioning module/
Battery pack
57 Transmission control module/
Engine control
module Fuses
Usage
58 Headlamps
74 Electric running boards (if
equipped)
76 Fuel pump prime / MGU motor
77 Cabin pump motor
79 Vacuum pump
Relays Usage
59 Fuel pump
60 Upfitter 2
61 Upfitter 3
62 Upfitter 4
63 Trailer parking lamps
64 Run/Crank
65 Upfitter 1
66 Fuel pump 2
67 Air conditioning control
68 Starter Relays
Usage
69 Rear window defogger
70 Engine control module
71 Vacuum pump/ Cooling fan clutch
72 CKT 95
73 CKT 92
75 Fuel pump prime/ MGU motor
78 Vacuum pump switch

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
392 Vehicle Care
The TIN shows the
manufacturer and plant code,
tire size, and date the tire was
manufactured. The TIN is
molded onto both sides of the
tire, although only one side may
have the date of manufacture.
(5) Tire Ply Material
:The type
of cord and number of plies in
the sidewall and under the tread.
(6) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required to
grade tires based on three
performance factors: treadwear,
traction, and temperature
resistance. For more
information, see Uniform Tire
Quality Grading 0410. (7) Maximum Cold Inflation
Load Limit
:Maximum load that
can be carried and the
maximum pressure needed to
support that load. For
information on recommended
tire pressure see Tire Pressure
0 397 and Vehicle Load Limits
0 248.
(8) Temporary Use Only
:Only
use a temporary spare tire until
the road tire is repaired and
replaced. This spare tire should
not be driven on over 112 km/h
(70 mph), or 88 km/h (55 mph)
when pulling a trailer, with the
proper inflation pressure. See
Full-Size Spare Tire 0425.
Light Truck (LT-Metric) Tire
(1) Tire Size:The tire size code
is a combination of letters and
numbers used to define a
particular tire's width, height,
aspect ratio, construction type,
and service description. See the
“Tire Size” illustration later in this
section for more detail.