2002 GMC SIERRA wiring

2-65 Air Bag Readiness Light
There is an air bag readiness light on the instrument
panel, which shows the air bag symbol. The system
checks the air bag's electrical system for malfunctions.
The light tells you if there is an electrical problem.
The system check includes the air bag sensors,
the air bag modules, the wiring, the passenger air bag
suppression circuit and the crash sensing and diagnostic
module. For more information on the air bag system,
see ªAir Bagº in the Index.
This light will come on
when you start your vehicle,
and it will flash for a few
seconds. Then the light
should go out. This means
the system is ready.
If the air bag readiness light stays on after you start the
vehicle or comes on when you are driving, your air bag
system may not work properly. Have your vehicle
serviced right away.
CAUTION:
If the air bag readiness light stays on after you
start your vehicle, it means the air bag system
may not be working properly. The air bags in
your vehicle may not inflate in a crash, or they
could even inflate without a crash. To help avoid
injury to yourself or others, have your vehicle
serviced right away if the air bag readiness light
stays on after you start your vehicle.
The air bag readiness light should flash for a few
seconds when you turn the ignition key to RUN.
If the light doesn't come on then, have it fixed so it
will be ready to warn you if there is a problem.

4-58 Trailer Wiring Harness
Heavy-Duty Trailer Wiring Package
Your pickup is equipped with the eight-wire trailer
towing harness. This harness with a seven
-pin universal
heavy
-duty trailer connector is attached to a bracket on
the hitch platform.
The Center High
-Mounted Stoplamp (CHMSL) wire is
tied next to the trailer wiring harness for use with a
trailer, slide
-in camper or cap.The eight
-wire harness contains the following
trailer circuits:

Yellow: Left Stop/Turn Signal

Dark Green: Right Stop/Turn Signal

Brown: Taillamps

White: Ground

Light Green: Back
-up Lamps

Light Blue: Center High
-Mounted
Stoplamp (CHMSL)

Red: Battery Feed

Dark Blue: Trailer Brake
A jumper harness for an electric trailer brake controller
and a trailer battery feed fuse are included with this
trailering package. (See ªInstrument Panel Jumper
Wiring Harnessº later in this section.)
If you need to tow a light
-duty trailer with a standard
four
-way round pin connector, an adapter connector is
included with your vehicle. See ªFour
-Wire Trailer
Harness Adapterº later in this section.

4-59
Instrument Panel Jumper Wiring Harness
This harness is included with the heavy-duty and
camper/fifth
-wheel trailer wiring packages. The harness
is for an electric trailer brake controller and includes a
trailer battery feed fuse. This harness and fuse should be
installed by your dealer or a qualified service center.Four Wire Trailer Harness Adapter
If you need to tow a light
-duty trailer with a standard
four
-way round pin connector, an adapter connector is
included with your vehicle.
Connect the adapter with
the tab (arrow) pointing
towards the top. The cap
on the wiring harness will
lock onto the tab (arrow)
and help hold the adapter
in place.

6-67 Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses, circuit breakers
and fusible thermal links. This greatly reduces the
chance of fires caused by electrical problems.
Look at the silver
-colored band inside the fuse. If the
band is broken or melted, replace the fuse. Be sure you
replace a bad fuse with a new one of the identical size
and rating.
If you ever have a problem on the road and don't have a
spare fuse, you can borrow one that has the same
amperage. Just pick some feature of your vehicle that
you can get along without
-- like the radio or cigarette
lighter
-- and use its fuse, if it is the correct amperage.
Replace it as soon as you can.Instrument Panel Fuse Block
The fuse block access door
is on the driver's side of the
instrument panel at the end.
Pull off the cover to access the fuse block.
You can remove fuses with a fuse extractor which is
mounted to the fuse block access door. To remove fuses
if you don't have a fuse extractor, hold the end of the
fuse between your thumb and index finger and pull it
straight out.
You may have spare fuses located behind the fuse block
access door. These can be used to replace a bad fuse.
However, make sure it is of the correct amperage.

6-70
Center Instrument Panel Fuse Block
The center instrument panel fuse block is located
underneath the instrument panel, to the left of the
steering column.Fuse Name Usage
SEO Special Equipment Option
HTD ST Heated Seats
SPARE Not Used
VANITY Headliner Wiring
TRAILER Trailer Brake Wiring
PWR ST Power Seats
SPARE Not Used
UPF Upfitter
PARK LAMP Parking Lamps
FRT PRK
EXPT*Not Used
SPARE 2 Not Used
PUDDLE LP Puddle Lamps
SL RIDE Not Used
SPARE 3 Not Used
INADV PWR Interior Lamps Feed
CTSY LP Courtesy Lamps
CEL PHONE Cellular Telephone Wiring

6-73
Fuse Usage
STUD #1 Accessory Power/Trailer Wiring
Feed/Load Leveling
ABS Anti
-Lock Brakes
IGN A Ignition Switch
AIR A.I.R. System
RAP #1 Retained Accessory Power, Power
Mirrors, Power Door Locks,
Power Seat(s)
IGN B Ignition Switch
RAP #2 Retained Accessory Power/Rear
Power Windows, Sunroof, Radio
STUD #2 Accessory Power/Trailer Wiring
Brake Feed
TRL R TRN Right Turn Signal Trailer Wiring
TRL L TRN Left Turn Signal Trailer Wiring
IGN 1 Ignition, Fuel Controls
INJ B Ignition, Fuel Controls (Relay)Fuse Usage
STARTER Starter (Relay)
PARK LP Parking Lamps
FRT HVAC Climate Control System
STOP LP Exterior Lamps, Stoplamps
ECM 1 VCM/PCM
CHMSL Center High Mounted Stoplamp
VEH STOP Stoplamps, Cruise Control
TRL B/U Backup Lamps Trailer Wiring
INJ A Fuel Controls, Ignition
RR HVAC Rear HVAC
VEH B/U Vehicle Backup Lamps
ENG 1 Engine Controls, Canister Purge,
Fuel System
ETC Electronic Throttle Control
IGN E A/C Compressor Relay, Rear
Window Defogger, Daytime
Running Lamps, A.I.R. System

6-74
Fuse Usage
B/U LP Backup Lamps, Automatic
Transmission Shift Lock
Control System
ATC Automatic Transfer Case
RR DEFOG Rear Window Defogger, Heated
Mirrors (Relay)
RTD Not Used
RR PRK Passenger's Side Parking Lamps
ECM B VCM/PCM
F/PMP Fuel Pump (Relay)
O2 A Oxygen Sensors
O2 B Oxygen Sensors
LR PRK Driver's Side Parking Lamps
RR DEFOG Rear Window Defogger,
Heated Mirrors
HDLP Headlamps (Relay)
TRL PRK Parking Lamps Trailer WiringFuse Usage
PRIME Not Used
RT HDLP Passenger's Side Headlamps
DRL Daytime Running Lamps (Relay)
HTD MIR Heated Mirrors
LT HDLP Driver's Side Headlamps
A/C Air Conditioning
AUX PWR Cigarette Lighter, Auxiliary
Power Outlets
SEO 2 Special Equipment Option Power,
Power Seats, Aux Roof Mnt Lamp
SEO 1 Special Equipment Option Power,
Aux Roof Mnt Lamp
DRL Daytime Running Lamps
A/C A/C (Relay)
FOG LP Fog Lamps
FOG LP Fog Lamps (Relay)
RADIO Audio System, Instrument Panel
Cluster, Climate Control System