fuel GMC SIERRA 1500 2015 Service Manual

Black plate (73,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Driving and Operating 9-73
SeeVehicle Load Limits on
page 9-15 for more information
about the vehicle's maximum load
capacity.
To identify the trailering capacity of
the vehicle, read the information in
“Weight of the Trailer” later in this
section.
Trailering is different than just
driving the vehicle by itself.
Trailering means changes in
handling, acceleration, braking,
durability, and fuel economy.
Successful, safe trailering takes
correct equipment, and it has to be
used properly.
The following information has many
time-tested, important trailering tips
and safety rules. Many of these are
important for your safety and that of
your passengers. Read this section
carefully before pulling a trailer.Weight of the Trailer
How heavy can a trailer safely be?
It depends on how the rig is used.
Speed, altitude, road grades,
outside temperature, and how much
the vehicle is used to pull a trailer
are all important. It can depend on
any special equipment on the
vehicle, and the amount of tongue
weight the vehicle can carry. See
“Weight of the Trailer Tongue” later
in this section for more information.
Trailer Weight Rating (TWR) is
calculated assuming the tow vehicle
has only the driver but all required
trailering equipment. Weight of
additional optional equipment,
passengers, and cargo in the tow
vehicle must be subtracted from the
trailer weight rating. For kingpin weight and trailer
tongue weight information, see
“Weight of the Trailer Tongue”
later
in this section.
Use the following chart to determine
how much the vehicle can weigh,
based upon the vehicle model and
options.
Weights listed apply for
conventional trailers and fifth-wheel
trailers unless otherwise noted.

Black plate (92,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
9-92 Driving and Operating
Operating the vehicle in Tow/Haul
when lightly loaded or with no trailer
at all will not cause damage.
However, there is no benefit to the
selection of Tow/Haul when the
vehicle is unloaded. Such a
selection when unloaded may result
in unpleasant engine and
transmission driving characteristics
and reduced fuel economy. Tow/
Haul is recommended only when
pulling a heavy trailer or a large or
heavy load.
Integrated Trailer Brake
Control System
The vehicle may have an Integrated
Trailer Brake Control (ITBC) system
for use with electric trailer brakes or
most electric over hydraulic trailer
brakes.
This symbol is on the Trailer Brake
Control Panel on vehicles with an
ITBC system. The power output to
the trailer brakes is based on the
amount of brake pressure being
applied by the vehicle’s brake
system, and on the type of trailer
brakes detected. This available
power output to the trailer brakes
can be adjusted to a wide range of
trailering situations.
The ITBC system is integrated with
the vehicle’s brake, antilock brake,
and StabiliTrak systems. In trailering
conditions that cause the vehicle’s
antilock brake or StabiliTrak
systems to activate, power sent to
the trailer's brakes will be
automatically adjusted to minimize
trailer wheel lock-up. This does not
imply that the trailer has StabiliTrak.
If the vehicle’s brake, antilock brake,
or StabiliTrak systems are not
functioning properly, the ITBC
system may not be fully functional
or may not function at all. Make sure all of these systems are fully
operational to ensure full
functionality of the ITBC system.
The ITBC system is powered
through the vehicle's electrical
system. Turning the ignition off will
also turn off the ITBC system. The
ITBC system is fully functional only
when the ignition is in ON/RUN.
{Warning
Connecting a trailer that has an
air brake system may result in
reduced or complete loss of trailer
braking. There may be an
increase in stopping distance or
trailer instability which could
result in personal injury or
damage to the vehicle, trailer,
or other property. Use the ITBC
system only with electric or
electric over hydraulic trailer
brakes.

Black plate (98,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
9-98 Driving and Operating
The plow the vehicle can carry
depends on many things, such as:
.The options the vehicle came
with, and the weight of those
options.
.The weight and number of
passengers intended to be
carried.
.The weight of items added to the
vehicle, like a tool box or
truck cap.
.The total weight of any
additional cargo intended to be
carried.
Say, for example, you have a 318 kg
(700 lb) snow plow. The total weight
of all occupants and cargo inside
the cab should not exceed 135 kg
(300 lb). This means that you may
only be able to carry one passenger.
But, even this may be too much if
there is other equipment already
adding to the weight of the vehicle. Here are some guidelines for safely
carrying a snow plow on the vehicle:
.Make sure the weight on the
front and rear axles does not
exceed the axle rating for each.
.For the front axle, if more cargo
or passengers must be carried,
appropriate counter ballast must
be installed rear of the rear axle.
Counter ballast must be properly
secured so it will not move
during driving.
.Follow the snow plow
manufacturer's
recommendations regarding rear
ballast. Rear ballast may be
required to ensure a proper front
and rear weight distribution ratio,
even though the actual weight at
the front axle may be less than
the front axle rating.
.The snow plow manufacturer or
installer can assist you in
determining the amount of rear
ballast required, to help make
sure the snow plow/vehicle
combination does not exceedthe GVW rating, the front and
rear axle ratings, and the front
and rear weight distribution ratio.
.The total vehicle must not
exceed the GVW rating.
Front axle reserve capacity is the
difference between the Gross Axle
Weight Rating (GAWR) and the front
axle weight of the vehicle with full
fuel and passengers. Basically, it is
the amount of weight that can be
added to the front axle before
reaching the front GAWR.

Black plate (100,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
9-100 Driving and Operating
This has the effect of reducing the
load on the front. However, the front
GAWR, rear GAWR, and Gross
Vehicle Weight Rating (GVWR) must
never be exceeded.
{Warning
On some vehicles that have
certain front mounted equipment,
such as a snow plow, it may be
possible to load the front axle to
the front gross axle weight rating
(GAWR) but not have enough
weight on the rear axle to have
proper braking performance. If the
brakes cannot work properly, you
could have a crash. To help the
brakes work properly when a
snow plow is installed, always
follow the snow plow
manufacturer or installer's
recommendation for rear ballast
to ensure a proper front and rear
weight distribution ratio, even
though the actual front weight(Continued)
Warning (Continued)
may be less than the front
GAWR, and the total vehicle
weight is less than the gross
vehicle weight rating (GVWR).
Maintaining a proper front and
rear weight distribution ratio is
necessary to provide proper
braking performance.
Total vehicle reserve capacity is the
difference between the GVWR and
the weight of the truck with full fuel
and passengers. It is the amount of
weight that can be added to the
vehicle before reaching the GVWR.
Keep in mind that reserve capacity
numbers are intended as a guide
when selecting the amount of
equipment or cargo the truck can
carry. If unsure of the vehicle's front,
rear, or total weight, go to a weigh
station and weigh the vehicle. Your
dealer can also help with this. The total vehicle reserve capacity
for the vehicle can be found in the
lower right corner of the
Certification/Tire label as shown
previously.
See your dealer for additional
advice and information about using
a snow plow on the vehicle. Also,
see
Vehicle Load Limits on
page 9-15.
Emergency Roof Lamp
Provisions
Vehicles with the RPO VYU snow
plow prep package also have an
emergency roof lamp provision
package, RPO TRW. Wiring for the
emergency roof lamp is provided
above the overhead console. See
Auxiliary Roof-Mounted Lamp on
page 6-5 for switch location.

Black plate (11,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Vehicle Care 10-11
Checking Engine Oil
It is a good idea to check the engine
oil level at each fuel fill. In order to
get an accurate reading, the vehicle
must be on level ground. The
engine oil dipstick handle is a loop.
SeeEngine Compartment Overview
on page 10-5 for the location of the
engine oil dipstick.
If a low oil message displays on the
DIC, it is important to park on level
ground to accurately measure the
oil level on the dipstick. Idling the
vehicle on steep grades for a long
time can influence the level sensing
accuracy.
Obtaining an accurate oil level
reading is essential:
1. If the engine has been running recently, turn off the engine and
allow several minutes for the oil
to drain back into the oil pan.
Checking the oil level too soon
after engine shutoff will not
provide an accurate oil level
reading.{Warning
The engine oil dipstick handle
may be hot; it could burn you.
Use a towel or glove to touch the
dipstick handle.
2. Pull out the dipstick and clean it with a paper towel or cloth, then
push it back in all the way.
Remove it again, keeping the tip
down, and check the level.
When to Add Engine Oil
If the oil is below the cross-hatched
area at the tip of the dipstick, add
1 L (1 qt) of the recommended oil
and then recheck the level. See
“Selecting the Right Engine Oil” in
this section for an explanation of what kind of oil to use. For engine
oil crankcase capacity, see
Capacities and Specifications on
page 12-2.
{Caution
Do not add too much oil. Oil
levels above or below the
acceptable operating range
shown on the dipstick are harmful
to the engine. If you find that you
have an oil level above the
operating range, i.e., the engine
has so much oil that the oil level
gets above the cross-hatched
area that shows the proper
operating range, the engine could
be damaged. You should drain
out the excess oil or limit driving
of the vehicle and seek a service
professional to remove the
excess amount of oil.
See Engine Compartment Overview
on page 10-5 for the location of the
engine oil fill cap.

Black plate (25,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Vehicle Care 10-25
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
attempting any repair. Repair the
cause of coolant loss, change the
oil, and reset the oil life system.
See
Engine Oil on page 10-10.
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

Black plate (44,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
10-44 Vehicle Care
J-CaseFuses Usage
13 Cooling Fan 2
Mini Fuses (2 Pin) Usage
14 Trailer Stop/Turn Lamps, Left
15 Trailer Parking Lamps
16 Trailer Back-up Lamp
17 Trailer Stop/Turn Lamps, Right
Micro Fuses (2 Pin) Usage
18 Fuel Pump
19 Integrated Chassis Control Module
20 Electronic Suspension
Control Module Micro Fuses
(2 Pin) Usage
21 Fuel Pump Power Module
22 Upfitter Switch 1
23 Upfitter 2
24 Front Wiper
25 Antilock Brake System Valves
26 Upfitter SW 2
27 Upfitter SW 3
28 Parking Lamps, Right
29 Parking Lamps, Left
30 Upfitter 3
31 Upfitter SW 4
32 Upfitter 4
33 Back-up Lamps
34 Engine Control Module Ignition Micro Fuses
(2 Pin) Usage
35 Air Conditioning Compressor 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
45 Fuel Injectors B, Even
46 Oxygen Sensor B
47 Throttle Control

Black plate (45,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Vehicle Care 10-45
Micro Fuses(2 Pin) Usage
48 Horn
49 Fog Lamp
50 Oxygen Sensor A
51 Engine Control Module
52 Interior Heater
53 Spare
54 Aeroshutter
55 Front Washer
Micro Fuses (3 Pin) Usage
56 Air Conditioning Compressor/
Battery Regulated
Voltage Control Micro Fuses
(3 Pin) Usage
57 Air Conditioning Compressor
Module/
Battery Pack
58 Transmission Control Module/
Engine Control
Module
59 Headlamps
Micro
Relays Usage
60 Fuel Pump
61 Upfitter 2
62 Upfitter 3
63 Upfitter 4
64 Trailer Parking Lamps
65 Run/Crank
66 Upfitter 1 Micro
Relays Usage
67 Fuel Pump 2
68 Air Conditioning Control
69 Starter
Mini Relays Usage 70 Rear Window Defogger
71 Engine Control Module
Solid State Relay Usage
72 Cooling Fan Clutch

Black plate (57,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Vehicle Care 10-57
(single/dual). The speed rating is
the maximum speed a tire is
certified to carry a load.
Tire Terminology and
Definitions
Air Pressure:The amount of
air inside the tire pressing
outward on each square inch of
the tire. Air pressure is
expressed in kPa (kilopascal)
or psi (pounds per square inch).
Accessory Weight
:The
combined weight of optional
accessories. Some examples of
optional accessories are
automatic transmission, power
windows, power seats, and air
conditioning.
Aspect Ratio
:The relationship
of a tire's height to its width. Belt
:A rubber coated layer of
cords between the plies and the
tread. Cords may be made from
steel or other reinforcing
materials.
Bead
:The tire bead contains
steel wires wrapped by steel
cords that hold the tire onto
the rim.
Bias Ply Tire
:A pneumatic tire
in which the plies are laid at
alternate angles less than
90 degrees to the centerline of
the tread.
Cold Tire Pressure
:The
amount of air pressure in a tire,
measured in kPa (kilopascal)
or psi (pounds per square inch)
before a tire has built up heat
from driving. See Tire Pressure
on page 10-59.
Curb Weight
:The weight of a
motor vehicle with standard and
optional equipment including the maximum capacity of fuel, oil,
and coolant, but without
passengers and cargo.
DOT Markings
:A code molded
into the sidewall of a tire
signifying that the tire is in
compliance with the U.S.
Department of Transportation
(DOT) Motor Vehicle Safety
Standards. The DOT code
includes the Tire Identification
Number (TIN), an alphanumeric
designator which can also
identify the tire manufacturer,
production plant, brand, and
date of production.
GVWR
:Gross Vehicle Weight
Rating. See Vehicle Load Limits
on page 9-15.
GAWR FRT
:Gross Axle Weight
Rating for the front axle. See
Vehicle Load Limits on
page 9-15.

Black plate (60,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
10-60 Vehicle Care
Caution (Continued)
.Reduced fuel economy.
Overinflated tires, or tires that
have too much air, can
result in:
.Unusual wear.
.Poor handling.
.Rough ride.
.Needless damage from
road hazards.
The Tire and Loading
Information label on the vehicle
indicates the original equipment
tires and the correct cold tire
inflation pressures. The
recommended pressure is the
minimum air pressure needed to
support the vehicle's maximum
load carrying capacity. For additional information
regarding how much weight the
vehicle can carry, and an
example of the Tire and Loading
Information label, see
Vehicle
Load Limits on page 9-15. How
the vehicle is loaded affects
vehicle handling and ride
comfort. Never load the vehicle
with more weight than it was
designed to carry.
When to Check
Check the tires once a month
or more.
Do not forget the spare tire,
if the vehicle has one. See
Full-Size Spare Tire on
page 10-87 for additional
information.
How to Check
Use a good quality pocket-type
gauge to check tire pressure.
Proper tire inflation cannot be
determined by looking at the tire. Check the tire inflation pressure
when the tires are cold, meaning
the vehicle has not been driven
for at least three hours or no
more than 1.6 km (1 mi).
Remove the valve cap from the
tire valve stem. Press the tire
gauge firmly onto the valve to
get a pressure measurement.
If the cold tire inflation pressure
matches the recommended
pressure on the Tire and
Loading Information label, no
further adjustment is necessary.
If the inflation pressure is low,
add air until the recommended
pressure is reached. If the
inflation pressure is high, press
on the metal stem in the center
of the tire valve to release air.
Re-check the tire pressure with
the tire gauge.
Return the valve caps on the
valve stems to prevent leaks
and keep out dirt and moisture.