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Heavy-DutyTrailer Wiring Harness
PackageFor vehicles equipped with heavy duty trailering, the
harness is connected to the trailer mounted to the hitch
platform. 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
* 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.
**If you are charging a remote (non-vehicle) battery,
turn on the headlamps to boost the vehicle system
voltage and properly charge the battery.
4-96
Page 400 of 580

Bulb Replacement..........................................5-62
Halogen Bulbs..............................................5-62
Headlamps..................................................5-63
Front Turn Signal, Sidemarker and Daytime
Running Lamps.........................................5-64
Roof Marker Lamps......................................5-66
Center High-Mounted Stoplamp (CHMSL)
and Cargo Lamp.......................................5-68
Pickup Box Identi cation and Fender
Marker Lamps...........................................5-69
Taillamps.....................................................5-69
Replacement Bulbs.......................................5-71
Windshield Wiper Blade Replacement..............5-72
Tires..............................................................5-73
Tire Sidewall Labelling...................................5-74
Tire Terminology and De nitions.....................5-77
In ation - Tire Pressure.................................5-80
Dual Tire Operation.......................................5-81
Tire Inspection and Rotation...........................5-82
When It Is Time for New Tires.......................5-84
Buying New Tires.........................................5-84
Uniform Tire Quality Grading..........................5-86
Wheel Alignment and Tire Balance..................5-87Wheel Replacement......................................5-87
Tire Chains..................................................5-89
If a Tire Goes Flat........................................5-90
Changing a Flat Tire.....................................5-91
Removing the Spare Tire and Tools................5-92
Removing the Flat Tire and Installing the
Spare Tire................................................5-96
Secondary Latch System..............................5-105
Storing a Flat or Spare Tire and Tools...........5-108
Spare Tire.................................................5-112
Appearance Care..........................................5-112
Cleaning the Inside of Your Vehicle...............5-113
Fabric/Carpet..............................................5-114
Leather......................................................5-115
Instrument Panel, Vinyl, and Other Plastic
Surfaces.................................................5-115
Care of Safety Belts....................................5-116
Weatherstrips.............................................5-116
Washing Your Vehicle..................................5-116
Cleaning Exterior Lamps/Lenses....................5-117
Finish Care................................................5-117
Windshield and Wiper Blades.......................5-118
Aluminum or Chrome-Plated Wheels..............5-118
Section 5 Service and Appearance Care
5-2
Page 461 of 580
Headlamps
To replace a headlamp bulb, do the following:
1. Open the hood. SeeHood Release on page 5-13
for more information.
2. If your vehicle is equipped with two pins, remove
the two pins on the top of the headlamp assembly.
To remove the pins, turn the outer pin outward
and pull it straight up. To remove the inner pin,
turn it in and pull it straight up.If your vehicle has one pin on the headlamp
assembly, remove the pin. To remove the pin,
turn the pin up and pull it out straight out.
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Page 462 of 580
A. Low-Beam Headlamp
B. High-Beam Headlamp
3. Pull the headlamp assembly out.
4. Unplug the electrical connector.
5. Turn the old bulb counterclockwise and remove it
from the headlamp assembly.
6. Install the new bulb into the assembly and turn it
clockwise until it is tight.
7. Plug in the electrical connector.
8. Reinstall the headlamp assembly.
9. Reinstall and tighten the two pins. If your vehicle
has one pin, reinstall it and turn it into the locking
feature.
Front Turn Signal, Sidemarker and
Daytime Running Lamps
A. Sidemarker Lamp
B. Retainer ClipC. Front Turn Signal Lamp
D. Daytime Running
Lamp (DRL)
5-64
Page 463 of 580
To replace a front turn signal, sidemarker or DRL bulb,
do the following:
1. Open the hood. SeeHood Release on page 5-13
for more information.
2. Remove the headlamp assembly as described
previously. SeeHeadlamps on page 5-63for
more information.
3. Press the retainer clip (B), located behind the turn
signal assembly, towards the outside of the vehicle.
4. Pull the turn signal assembly out of the vehicle.5. Press the locking release lever, turn the bulb socket
counterclockwise and remove it from the turn signal
assembly.
6. Remove the old bulb from the bulb socket.
7. Install a new bulb into the bulb socket.
8. Insert the bulb socket into the turn signal assembly
and turn it clockwise until it locks.
9. Reinstall the turn signal assembly back into the
vehicle placing the hook and posts on the inner
side into the alignment holes rst, then the
outer side into the retainer bracket until you hear
a click.
10. Reinstall the headlamp assembly.
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Page 469 of 580
Taillamps (Chassis Cab Models)
A. Turn Signal Lamp
B. Taillamp/Stoplamp
C. Back-up Lamp
To replace one of these bulbs for chassis cab models,
do the following:
1. Peel the rubber seal away from the lens using
your hands.
2. Lift the lens off the lamp assembly.
3. Pull the old bulb straight out from the socket.
4. Install a new bulb into the socket and press it in
until it is tight.
5. Reinstall the lens and the lens seal.
Replacement Bulbs
Exterior Lamp Bulb Number
Back-up Lamp 3157
Back-up Lamp* 1156
Cargo Lamp 912
Center High-Mounted Stoplamp
(CHMSL)912
Daytime Running Lamps (DRL) 4114K
Fender Marker Lamps 194
Front Parking and Turn Lamp 3457A
Front Roof Marker Lamps 194
Headlamps
High-Beam 9005
Low-Beam 9006
Rear Marker Lamp, Taillamp and
Stoplamp*3157
Rear Turn Signal Lamp 3157
Rear Turn Signal Lamp* 1156
Sidemarker Lamp (If Equipped) 194
Stoplamp and Taillamp* 1157
* Chassis Cab Models
For replacement bulbs not listed here, contact your
dealer.
5-71
Page 486 of 580

Each new wheel should have the same load-carrying
capacity, diameter, width, offset and be mounted
the same way as the one it replaces.
If you need to replace any of your wheels, wheel bolts or
wheel nuts, replace them only with new GM original
equipment parts. This way, you will be sure to have the
right wheel, wheel bolts and wheel nuts for your vehicle.
{CAUTION:
Using the wrong replacement wheels, wheel
bolts or wheel nuts on your vehicle can be
dangerous. It could affect the braking and
handling of your vehicle, make your tires lose
air and make you lose control. You could have
a collision in which you or others could be
injured. Always use the correct wheel, wheel
bolts and wheel nuts for replacement.
Notice:The wrong wheel can also cause problems
with bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper height,
vehicle ground clearance and tire or tire chain
clearance to the body and chassis.Whenever a wheel, wheel bolt or wheel nut is replaced
on a dual wheel setup, check the wheel nut torque
after 100, 1,000 and 6,000 miles (160, 1 600 and
10 000 km) of driving. For proper torque, see “Wheel
Nut Torque” underCapacities and Speci cations
on page 5-133.
SeeChanging a Flat Tire on page 5-91for more
information.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You cannot know how it has been
used or how far it has been driven. It could fail
suddenly and cause a crash. If you have to
replace a wheel, use a new GM original
equipment wheel.
5-88
Page 528 of 580
Fuses Usage
S/ROOF Sunroof
SEO B2 Off-Road Lamps
4WSVent Solenoid Canister/
QUADRASTEER™ Module
Power
RR HVAC Not Used
AUX PWRAuxiliary Power
Outlet — Console
IGN 1 Ignition Relay
PCM 1 Powertrain Control Module
ETC/ECMElectronic Throttle Control,
Electronic Brake Controller
IGN EInstrument Panel Cluster,
Air Conditioning Relay,
Turn Signal/Hazard Switch,
Starter Relay
RTD Ride Control
TRL B/U Backup Lamps Trailer Wiring
PCM BPowertrain Control Module,
Fuel Pump
F/PMP Fuel Pump (Relay)Fuses Usage
B/U LPBack-up Lamps, Automatic
Transmission Shift Lock
Control System
RR DEFOG Rear Window Defogger
HDLP-HI Headlamp High Beam Relay
PRIME Not Used
02B Oxygen Sensors
AIRBAGSupplemental In atable
Restraint System
FRT PARKFront Parking Lamps,
Sidemarker Lamps
DRLDaytime Running Lamps
(Relay)
SEO IGN Rear Defog Relay
TBC IGN1 Truck Body Controller Ignition
HI HDLP-LT High Beam Headlamp-Left
LH HID Not Used
DRL Daytime Running Lamps
RVC Regulated Voltage Control
5-130