2004 GMC SIERRA Battery

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: CHMSL
·Red: Battery Feed
·Dark Blue: Trailer Brake
If your trailer is equipped with electric brakes, you can
get a jumper harness (electric trailer brake control)
with a trailer battery feed fuse from your dealer.
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.
Camper/Fifth-Wheel Trailer Wiring Package
The eight-wire camper harness is located under the
front edge of the pickup box on the driver's side of the
vehicle, attached to the frame bracket. A connector
will have to be added to the wiring harness which
connects to the camper.
The eight-wire harness contains the following
camper/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
4-97

This harness is included with your vehicle as part of the
heavy-duty trailer wiring package.
This harness is for an electric brake controller and
includes a trailer battery feed fuse. It should be installed
by your dealer or a quali®ed service center.
Four-Wire Harness Adapter
This adapter is included
with your vehicle as part of
the heavy-duty trailer
wiring package.
Use this adapter to connect a standard four-way round
pin connector to the seven-wire harness on your
vehicle.
4-99

Connect the adapter with the tab pointing up (see
arrow). The ¯ip cap on the vehicle's seven-wire harness
will lock onto the tab and help hold the adapter in
place. Plug the four-way round pin connector onto the
adapter.
Auxiliary Battery
The auxiliary battery provision can be used to supply
electrical power to additional equipment that you
may choose to add, such as a slide-in camper.If your vehicle has this
provision, this relay will be
located on the passenger's
side of the vehicle, next
to the auxiliary battery.
When using this provision, connection should only be
made to the upper stud (A) of the relay. Do not
make connections to the lower stud (B) of the relay.
The auxiliary battery circuit is protected by a megafuse
located behind the auxiliary battery.
Be sure to follow the proper installation instructions that
are included with any electrical equipment that you
install.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 exceeds the maximum
amperage rating for the auxiliary battery provision.
4-100

Service............................................................5-3
Doing Your Own Service Work.........................5-3
Adding Equipment to the Outside of Your
Vehicle......................................................5-4
Fuel................................................................5-4
Gasoline Octane............................................5-4
Gasoline Speci®cations....................................5-5
California Fuel...............................................5-5
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-6
Filling Your Tank............................................5-7
Filling a Portable Fuel Container.......................5-9
Checking Things Under the Hood....................5-10
Hood Release..............................................5-10
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-18
Engine Air Cleaner/Filter................................5-23
Automatic Transmission Fluid (Except Allison
Transmission
ž) ..........................................5-25
Automatic Transmission Fluid (Allison
Transmission
ž) ..........................................5-28
Manual Transmission Fluid.............................5-31
Hydraulic Clutch...........................................5-32
Engine Coolant.............................................5-33
Coolant Surge Tank Pressure Cap..................5-36
Engine Overheating.......................................5-36Cooling System............................................5-39
Engine Fan Noise.........................................5-44
Power Steering Fluid.....................................5-45
Windshield Washer Fluid................................5-46
Brakes........................................................5-48
Battery........................................................5-52
Jump Starting...............................................5-53
Rear Axle.......................................................5-59
Four-Wheel Drive............................................5-60
Noise Control System.....................................5-62
Tampering with Noise Control System
Prohibited.................................................5-62
Bulb Replacement..........................................5-64
Halogen Bulbs..............................................5-64
Headlamps..................................................5-64
Front Turn Signal, Sidemarker and Daytime
Running Lamps.........................................5-66
Roof Marker Lamps......................................5-67
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp.............................................5-69
Pickup Box Identi®cation and Fender Marker
Lamps.....................................................5-70
Taillamps.....................................................5-71
Replacement Bulbs.......................................5-74
Section 5 Service and Appearance Care
5-1

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-23.
B. Coolant Surge Tank. See
Engine Coolant on
page 5-33.
C. Air Filter Restriction Indicator (If Equipped). See
Engine Air Cleaner/Filter on page 5-23.
D. Engine Oil Dipstick. See
Engine Oil on page 5-18.
E. Automatic Transmission Dipstick (If equipped).
See
Automatic Transmission Fluid (Except Allison
Transmissionž) on page 5-25orAutomatic
Transmission Fluid (Allison Transmissionž)on
page 5-28.
F. Fan. See
Cooling System on page 5-39.
G. Engine Oil Fill. See
Engine Oil on page 5-18.H. Power Steering Fluid Reservoir. See
Power Steering
Fluid on page 5-45.
I. Remote Negative (-) Terminal (GND). See
Jump
Starting on page 5-53.
J. Remote Positive (+) Terminal. See
Jump Starting on
page 5-53.
K. Brake Fluid Reservoir. See
Brakes on page 5-48.
L. Clutch Fluid Reservoir (If Equipped). See
Hydraulic
Clutch on page 5-32.
M. Underhood Fuse Block. See
Fuses and Circuit
Breakers on page 5-126.
N. Battery. See
Battery on page 5-52.
O. Windshield Washer Fluid Reservoir. See
Windshield
Washer Fluid on page 5-46.
5-13

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-23.
B. Coolant Surge Tank. See
Engine Coolant on
page 5-33.
C. Air Filter Restriction Indicator (If Equipped). See
Engine Air Cleaner/Filter on page 5-23.
D. Engine Oil Dipstick. See
Engine Oil on page 5-18.
E. Automatic Transmission Dipstick (If Equipped).
See
Automatic Transmission Fluid (Except Allison
Transmissionž) on page 5-25orAutomatic
Transmission Fluid (Allison Transmissionž)on
page 5-28.
F. Engine Oil Fill. See
Engine Oil on page 5-18.
G. Fan. See
Cooling System on page 5-39.H. Remote Negative (-) Terminal (GND). See
Jump
Starting on page 5-53.
I. Power Steering Fluid Reservoir. See
Power Steering
Fluid on page 5-45.
J. Remote Positive (+) Terminal. See
Jump Starting on
page 5-53.
K. Brake Fluid Reservoir. See
Brakes on page 5-48.
L. Clutch Fluid Reservoir (If Equipped). See
Hydraulic
Clutch on page 5-32.
M. Underhood Fuse Block. See
Fuses and Circuit
Breakers on page 5-126.
N. Battery. See
Battery on page 5-52.
O. Windshield Washer Fluid Reservoir. See
Windshield
Washer Fluid on page 5-46.
5-15

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-23.
B. Coolant Surge Tank. See
Engine Coolant on
page 5-33.
C. Air Filter Restriction Indicator (If Equipped). See
Engine Air Cleaner/Filter on page 5-23.
D. Engine Oil Dipstick. See
Engine Oil on page 5-18.
E. Automatic Transmission Dipstick (If Equipped).
See
Automatic Transmission Fluid (Except Allison
Transmissionž) on page 5-25orAutomatic
Transmission Fluid (Allison Transmissionž)on
page 5-28.
F. Engine Oil Fill. See
Engine Oil on page 5-18.
G. Fan. See
Cooling System on page 5-39.H. Remote Negative (-) Terminal (GND). See
Jump
Starting on page 5-53.
I. Remote Positive (+) Terminal. See
Jump Starting on
page 5-53.
J. Power Steering Fluid Reservoir. See
Power Steering
Fluid on page 5-45.
K. Brake Fluid Reservoir. See
Brakes on page 5-48.
L. Clutch Fluid Reservoir (If Equipped). See
Hydraulic
Clutch on page 5-32.
M. Underhood Fuse Block. See
Fuses and Circuit
Breakers on page 5-126.
N. Battery. See
Battery on page 5-52.
O. Windshield Washer Fluid Reservoir. See
Windshield
Washer Fluid on page 5-46.
5-17

Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together if
the vehicle is to have really good braking. Your
vehicle was designed and tested with top-quality GM
brake parts. When you replace parts of your braking
system Ð for example, when your brake linings
wear down and you need new ones put in Ð be sure
you get new approved GM replacement parts. If you do
not, your brakes may no longer work properly. For
example, if someone puts in brake linings that are wrong
for your vehicle, the balance between your front and
rear brakes can change Ð for the worse. The braking
performance you have come to expect can change
in many other ways if someone puts in the wrong
replacement brake parts.
Battery
Your new vehicle comes with a maintenance free
ACDelcožbattery. When it is time for a new battery, get
one that has the replacement number shown on the
original battery's label. We recommend an ACDelco
ž
battery. SeeEngine Compartment Overview on
page 5-12for battery location.
Warning:Battery posts, terminals and related
accessories contain lead and lead compounds,
chemicals known to the State of California to cause
cancer and reproductive harm. Wash hands after
handling.
Vehicle Storage
If you are not going to drive your vehicle for 25 days or
more, remove the black, negative (-) cable from
the battery. This will help keep your battery from
running down.
{CAUTION:
Batteries have acid that can burn you and gas
that can explode. You can be badly hurt if you
are not careful. See
Jump Starting on
page 5-53
for tips on working around a battery
without getting hurt.
Contact your dealer to learn how to prepare your
vehicle for longer storage periods.
Also, for your audio system, see
Theft-Deterrent
Feature on page 3-127.
5-52