Page 39 of 534

Black plate (33,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
In Brief 1-33
Driving for Better Fuel
Economy
Driving habits can affect fuel
mileage. Here are some driving tips
to get the best fuel economy
possible.
.Avoid fast starts and accelerate
smoothly.
.Brake gradually and avoid
abrupt stops.
.Avoid idling the engine for long
periods of time.
.When road and weather
conditions are appropriate, use
cruise control.
.Always follow posted speed
limits or drive more slowly when
conditions require.
.Keep vehicle tires properly
inflated.
.Combine several trips into a
single trip.
.Replace the vehicle's tires with
the same TPC Spec number
molded into the tire's sidewall
near the size.
.Follow recommended scheduled
maintenance.
Roadside Assistance
Program
U.S.: 1-888-881-3302
TTY Users (U.S. Only):
1-888-889-2438
Canada: 1-800-268-6800
Mexico: 01-800-466-0801
As the owner of a new GMC, you
are automatically enrolled in the
Roadside Assistance program.
SeeRoadside Assistance Program
(Mexico) on page 13‑7 orRoadside
Assistance Program (U.S. and
Canada) on page 13‑11. Roadside Assistance and OnStar
(U.S. and Canada)
If the vehicle has an active OnStar
subscription, contact OnStar and the
vehicle’s current GPS location will
be sent to an OnStar advisor to
assess the situation, contact
Roadside Assistance, and relay the
exact location to send help.OnStar®
If equipped, this vehicle has a
comprehensive, in-vehicle system
that can connect to a live Advisor
for Emergency, Security, Navigation,
Connection, and Diagnostic
Services. See
OnStar Overview on
page 14‑1.
Page 357 of 534

Black plate (91,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
Driving and Operating 9-91
Fifth-wheel or gooseneck kingpin
weight should be 15 to 25 percent of
the trailer weight up to the maximum
amount specified in the trailering
chart for the vehicle. See“Weight of
the Trailer” underTrailer Towing on
page 9‑73 for more information.
The hitch should be located in the
pickup bed so that its centerline is
over or slightly in front of the rear
axle. Take care that it is not so far
forward that it will contact the back
of the cab in sharp turns. This is
especially important for short box
pickups. Trailer pin box extensions
and sliding fifth-wheel hitch
assemblies can help this condition.
There should be at least six inches
of clearance between the top of the
pickup box and the bottom of the
trailer shelf that extends over
the box.
Make sure the hitch is attached to
the tow vehicle frame rails. Do not
use the pickup box for support.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.
Instructions about safety chains
may be provided by the hitch
manufacturer or by the trailer
manufacturer. If the trailer being
towed weighs up to 2 271 kg
(5,000 lbs) with a factory-installed
step bumper, safety chains may be
attached to the attaching points on
the bumper; otherwise, safety
chains should be attached to holes
on the trailer hitch platform. Always
leave just enough slack so the
combination can turn. Never allow
safety chains to drag on the ground.
Trailer Brakes
A loaded trailer that weighs more
than 900 kg (2,000 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.
Do not tap into the vehicle's
hydraulic brake system.
Auxiliary Battery
The auxiliary battery provision can
be used to supply electrical power
to additional equipment that may be
added, such as a slide-in camper.
If the vehicle has this provision, this
relay will be located on the driver
side of the vehicle, next to the
underhood electrical center.
Be sure to follow the proper
installation instructions included with
any electrical equipment that is
installed.
Notice:
Leaving electrical
equipment on for extended
periods will drain the battery.
Always turn off electrical
equipment when not in use and
do not use equipment that
Page 413 of 534
Black plate (43,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
Vehicle Care 10-43
J-CaseFuses Usage
68 Stud 1 (Trailer Connector Battery
Power) (Optional -
40A Fuse
Required)
69 Mid-Bussed Electrical Center 1
70 Climate Control Blower
71 Not Used
72 Left Bussed Electrical Center 2
Relays Usage
FAN HI Cooling Fan High Speed
FAN LO Cooling Fan Low Speed
FAN CNTRL Cooling Fan Control Relays Usage
HDLP
LO/HID Low-Beam
Headlamp
FOG LAMP Front Fog Lamps
A/C
CMPRSR Air Conditioning
Compressor
STRTR Starter
PWR/TRN Powertrain
FUEL PMP Fuel Pump
PRK LAMP Parking Lamps
REAR
DEFOG Rear Defogger
RUN/CRNK Switched PowerInstrument Panel Fuse
Block
The instrument panel fuse block
access door is located on the driver
side edge of the instrument panel.
Pull off the cover to access the fuse
block.
Page 414 of 534
Black plate (44,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
10-44 Vehicle Care
The vehicle may not be equipped
with all of the fuses, relays, and
features shown.Fuses Usage
1 Rear Seats
2 Rear Accessory Power Outlet Fuses Usage
3 Steering Wheel Controls Backlight
4 Driver Door Module
5 Dome Lamps, Driver Side Turn Signal Fuses Usage
6 Driver Side Turn Signal, Stoplamp
7 Instrument Panel Back Lighting
8 Passenger Side Turn Signal, Stoplamp
9 Passenger Door Module, Driver Unlock
10 Power Door Lock 2 (Unlock Feature)
11 Power Door Lock 2 (Lock Feature)
12 Stoplamps, Center High‐Mounted
Stoplamp
13 Rear Climate Controls
14 Power Mirror
15 Body Control Module (BCM)
16 Accessory Power Outlets