2018 GMC SIERRA relay

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Driving and Operating 327
Fifth-wheel or gooseneck kingpin
weight should be 15 to 25% of the
trailer weight up to the maximum
amount specified in the trailering
chart for the vehicle. See“Weight of
the Trailer” underTrailer Towing
0 307.
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 15 cm (6 in)
of clearance between the top of the
pickup box and the bottom of the
trailer shelf that extends over
the box.
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 is being
towed 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 lb) must be
equipped with its own brake system,
with brakes working on all axles.
Trailer braking equipment
conforming to Canadian Standards
Association (CSA) requirement
CAN3-D313, or its equivalent, is
recommended.
State and local regulations may also
require the trailer to have its own
braking system if loaded above a
certain threshold. These
requirements vary from state to
state.
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 equipped, this relay will be 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.

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
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
Vehicle Care 385
Instrument Panel Fuse
Block (Right)
The right instrument panel fuse
block access door is on the
passenger side edge of the
instrument panel.
Pull off the cover to access the fuse
block.
The vehicle may not be equipped
with all of the fuses, relays, and
features shown.Fuses Usage
1 Accessory power outlet 3

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
386 Vehicle Care
FusesUsage
2 Accessory power outlet 4
7 Body control module 4
8 Body control module 8
9 Rear seat entertainment
10 Cargo lamp
15 Steering wheel controls
18 Radio
19 –
20 Sunroof
23 Airbag/Info
26 Export/Power take off/ Special equipment
option/Battery 1
27 Obstacle detection/ USB ports
28 Body control module 2
32 Special equipment option/Battery 2 Fuses
Usage
35 Air conditioning inverter
36 Amplifier
37 Battery system
39 Rear sliding window
42 Right door window motor
43 Front blower
44 Special equipment option
45 Body control module 6
46 Body control module 7
47 Passenger seat
Relays Usage
50 Retained accessory power
51 Rear sliding window open
52 Rear sliding window closeInstrument Panel Fuse
Block (Left)
The left instrument panel fuse block
access door is on the driver side
edge of the instrument panel.
Pull off the cover to access the fuse
block.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 387
The vehicle may not be equipped
with all of the fuses, relays, and
features shown.Fuses Usage
1 Accessory power outlet 2 Fuses Usage
2 Special equipment option/Retained
accessory power
3 Universal remote system/Interior
rearview mirror
6 Body control module 3
7 Body control module 5
8 Driver window switch/ Mirror switch
9 –
10 Accessory power outlet/Retained
accessory power
11 Accessory power outlet battery
12 Accessory power outlet 1/Cigarette
lighter
13 Discrete logic ignition switch
14 Switch backlighting
17 Body control module 1

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
388 Vehicle Care
FusesUsage
19 –
20 –
22 Heating, ventilation, and air conditioning/
Auxiliary heating,
ventilation, and air
conditioning/Ignition
23 Instrument cluster/ Ignition sensing
diagnostic module/
Ignition
24 –
25 Data link connector/ Driver seat module
26 Passive entry/Passive start/Heating,
ventilation, and air
conditioning
27 – Fuses
Usage
28 –
29 Park enable/ Electrically adjustable
pedals
30 Special equipment option
31 Accessory/Run/Crank
32 Heated steering wheel
33 –
34 Instrument cluster
36 –
37 –
38 4WD transfer case electronic control
40 Left doors
41 Driver power seat Fuses
Usage
43 Left heated, cooled or ventilated seats (if
equipped)
44 Right heated, cooled or ventilated seats (if
equipped)
45 –
Relays Usage
49 Retained accessory power
50 Run/Crank

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
480 OnStar
Press=to:
. Open the OnStar app on the
infotainment display. See the
infotainment manual for
information on how to use the
OnStar app.
Or
. Make a call, end a call,
or answer an incoming call.
. Give OnStar Hands-Free Calling
voice commands.
. Give OnStar Turn-by-Turn
Navigation voice commands.
. Obtain and customize the Wi-Fi
hotspot name or SSID and
password, if equipped.
Press
Qto connect to an
Advisor to:
. Verify account information or
update contact information. .
Get driving directions.
. Receive a Diagnostic check of
the vehicle's key operating
systems.
. Receive Roadside Assistance.
. Manage Wi-Fi Settings,
if equipped.
Press
>to get a priority connection
to an OnStar Advisor available
24/7 to:
. Get help for an emergency.
. Be a Good Samaritan or
respond to an AMBER Alert.
. Get assistance in severe
weather or other crisis situations
and find evacuation routes.
OnStar Services
Emergency
Emergency Services require an
active, OnStar service plan
(excludes Basic Plan). With
Automatic Crash Response, built-in
sensors can automatically alert a
specially trained OnStar Advisor
who is immediately connected in to
the vehicle to help.
Press
>for a priority connection to
an OnStar Advisor who can contact
emergency service providers, direct
them to your exact location, and
relay important information.
With OnStar Crisis Assist, specially
trained Advisors are available
24 hours a day, 7 days a week, to
provide a central point of contact,
assistance, and information during a
crisis.
With Roadside Assistance, Advisors
can locate a nearby service provider
to help with a flat tire, a battery
jump, or an empty gas tank.