2003 GMC SIERRA DENALI wiring

Air Bag Readiness Light
There is an air bag readiness light on the instrument
panel cluster, 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 passenger sensing
system
(if equipped), the wiring and the crash sensing
and diagnostic module. For more information on the
air bag system, see
Air Bag Systems on page 1-57.
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.
3-27

Trailer Wiring Harness
Your pickup is equipped with the eight-wire trailer
towing harness. This harness with a seven-pin universa
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 Stopnurn Signal
Dark Green: Right Stopnurn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Light Blue: Center High-Mounted Stoplamp
(CHMSL)
Red: Battery Feed
Dark Blue: Trailer Brake
If your trailer
is equipped with electrical brakes, you can
get a jumper harnesdelectric trailer brake control
with a trailer battery feed fuse from your dealer. This
harness and fuse should be installed by your dealer or a
qualified service center.
If you need to tow a light-duty trailer with a standard
four-way round pin connector, you can also get an
adapter from your dealer.
4-60

Electrical System
Add-on Electrical Equipment
Notice: Don’t add anything electrical to your
vehicle unless you check with your dealer first.
Some electrical equipment can damage your vehicle
and the damage wouldn’t be covered by your
warranty. Some add-on electrical equipment can
keep other components from working as they
should.
Your vehicle has an air bag system. Before attempting
to add anything electrical to your vehicle, see
Servicing Your Air Bag-Equipped Vehicle on page 1-72.
Windshield Wiper Fuses
The windshield wiper motor is protected by an internal
circuit breaker and a fuse.
If the motor overheats due to
heavy snow, etc., the wiper will stop until the motor
cools. If the overload
is caused by some electrical
problem and not snow, etc., be sure to get it fixed.
Power Windows and Other Power
Options
Circuit breakers protect the power windows and other
power accessories. When the current load
is too heavy,
the circuit breaker opens and closes, protecting the
circuit until the problem is fixed or goes away.
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.
5-95

Center Instrument Panel Fuse Block
The center instrument panel utility block is located
underneath the instrument panel, to the left of the
steering column.
Device Special Equipment ODtion
SEO Usage
TRAILER Upfitter (Not Used)
UPFIT Trailer
Brake Wiring
1 SL RIDE I
Ride Control Harness
Connection
I Device I Usage I
HDLR 2
Bodv Wiring Connector
BODY Headliner Wiring
connector-
DEFOG Headliner Wiring Connector
1 HDLNR 1
Rear Defogger Relay
I SPARE RELAY I Not Used I
CB SEAT Driver
and Passenger Seat
Module Circuit Breaker
I CB RT DOOR I
Right Power Windows Circuit
Breaker
I
I SPARE I Not Used I
I INFO I
~-
Infotainment Harness
Connection
1
5-98

*I - Gasoline Engine and Diesel Engine.
*2 - Gasoline Engine; ECMRPV - Diesel Engine.
*3 - Gasoline Engine; FUEL HT - Diesel Engine.
*4 - Gasoline Engine; ECM f - Diesel Engine.
*5 - IGN/EDU
r Fuses
GLOW PLUG
CUST FEED
STUD
#I
MBEC
BLOWER
LBEC Only)/ Dual Battery
(TP2)
Do not install fuse.
Mid Bussed Electrical Center
Power Feed, Front Seats,
Riaht Doors TRL
PARK Parking Lamps Trailer Wiring
RR PARK Right
Rear Parking and
Sidemarker LamDs
TBC BATT Truck Body
Controller Battery
I Feed
5-1 01

Fuses Usage
4WS Canister/QUADRASTEERTM
RR HVAC Not Used
Vent
Solenoid
Module Power
AUX PWR IGN
1 Ignition Relay
PCM
1
Auxiliary Power
Outlet
- Console
Electronic Throttle Control,
IGN E
Rday
RTD Ride Control
TRL B/U
PCM B
~~ ~-
Backup Lamps Trailer Wiring
Powertrain Control Module,
Fuel Pump
-. - . . -. . . .
F/PM P
B/U LP Transmission Shift Lock
r
Fuel Pump (Relay)
Back-up Lamps, Automatic
Control System
RR DEFOG Rear Window Defogger SIR
FRT PARK
DRL Daytime Running Lamps
I (Relav)
SEO IGN
TBC IGNI Truck Body Controller Ignition \~ ------I
Rear Defog Relay
HI HDLP-LT High Beam Headlamp-Left
LH HID Not Used
DRL Daytime Running Lamps
IPC/DIC Instrument
Panel
Cluster/Driver Information Center
5-1 02

Taillamps ....................................................... 5-58
Temperature and Compass Display
.................... 2-28
Testing the Alarm
............................................ 2-14
Theft.Deterrent. Radio
..................................... 3-81
Theft-Deterrent Systems
................................... 2-1 3
Content Theft-Deterrent
................................ 2-1 3
Passlock@
................................................... 2-1 4
Tilt Wheel
........................................................ 3-4
Tire Inflation Check
......................................... 6-10
Tires
..................................................... 5.61. 5-90
Buying New Tires
........................................ 5-64
Chains
....................................................... 5-68
Changing a Flat Tire
.................................... 5-69
If a Tire Goes Flat ....................................... 5-68
Inflation
- Tire Pressure ............................... 5-62
Inspection and Rotation
................................ 5-62
Spare Tire
.................................................. 5-85
Uniform Tire Quality Grading
......................... 5-65
Wheel Alignment and Tire Balance
................. 5-67
Wheel Replacement
..................................... 5-67
When It
Is Time for New Tires ...................... 5-64
To Use the Engine Coolant Heater .................... 2-18
Tonneau Cover
............................................ 2-39
Top of the Instrument Panel
.......... ........ 5-87
Top Strap
...................................................... 1-40
Top Strap Anchor Location
............................... 1-41
Torque Lock
................................................... 2-25
Total Weight on Your Vehicle’s Tires
.................. 4-55 Tow/Haul
Mode
............................................... 2-21
Tow/Haul Mode Light
....................................... 3-41
Towing Recreational Vehicle
..................................... 4-45
Towing a Trailer
.......................................... 4-51
Your Vehicle
............................................... 4-45
TRACTION ACTIVE
.................................... 3-58
Trailer Recommendations
....................................... 4-50
Trailer Brakes
................................................. 4-56
Trailer Wiring Harness
..................................... 4-60
Transfer Case
................................................ 5-49
Transmission Fluid, Automatic
.......................... ......... 5-21
Temperature Gage
....................................... 3-36
TRANSMISSION HOT
..................................... 3-59
Transmission Operation, Automatic
.................... 2-18
Transmission, Transaxle, Transfer Case Unit Repair Manual
............................................ 7-10
Transportation Options
...................................... 7-7
Trip Information Button
....................... ..... 3-44
Trip Odometer
................................................ 3-26
Truck-Camper Loading Information
.................... 4-48
Turn and Lane Change Signals
.......................... 3-5
Turn SignaVMultifunction Lever ........................... 3-5
Turn Signals When Towing a Trailer
.................. 4-57
Two-Tiered Loading
......................................... 4-47
TURN
SIGNAL ON
......................................... 3-56
14