Exterior Lamps
The control located to the left of the steering column
operates the exterior lamps.
The exterior lamp control has three positions:
OFF:Turning the control to this position turns off all
lamps except the Daytime Running Lamps (DRL).
;(Parking Lamps):Turning the control to this
position turns on the parking lamps, together with
the following:
•Marker Lamps
•Taillamps
•License Plate Lamps
•Instrument Panel Lights
O(Headlamps):Turning the control to this position
turns on the headlamps, together with the previously
listed lamps and lights.
You can switch your headlamps from low to high beam
by pulling the turn signal/multifunction lever toward
you. Pull the lever toward you again to return to
low beam.
A circuit breaker protects your headlamps. If you have
an electrical overload, your headlamps will flicker on and
off. Have your headlamp wiring checked right away if
this ever happens.
3-14
Engine Road Speed Governor
This system controls maximum vehicle speed
automatically and reduces engine power until vehicle
speed gets down to maximum governed speed.
The default setting for C4500 and C5500 models up to
19,500 lbs GVWR is 80 to 85 mph (128 to 136 km/h).
Most other models have a default setting of 75 mph
(120 km/h), although some tire sizes and tread patterns
may limit maximum speed to 55 to 65 mph
(86 to 105 km/h). You may have a label on the headliner
of your vehicle with more information on your engine road
speed governor. See your GM dealer for assistance with
programming your engine limited speed.
Safety Belt Reminder Light
When the key is turned to RUN or START, a light will
come on for several seconds to remind people to fasten
their safety belts.
The safety belt light will
also come on and stay on
for several seconds.
Safety Belt Reminder Tone
If your vehicle has this feature, when you turn your key
to RUN or START, a tone will sound for several
seconds to remind people to fasten their safety belts.
Airbag Readiness Light
If your vehicle has airbags, there is an airbag readiness
light on the instrument panel, which shows the airbag
symbol. The system checks the airbag’s electrical
system for malfunctions. The light tells you if there is an
electrical problem. The system check includes the
airbag sensors, the airbag modules, the wiring, the
passenger airbag suppression circuit and the crash
sensing and diagnostic module. For more information on
the airbag system, seeAirbag System on page 1-48.
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.
3-27
Trailer Connections
Heavy-Duty Trailer Wiring Package
Your vehicle may be equipped with an eight-wire trailer
towing harness. This harness, with a seven-pin
universal heavy-duty trailer connector, is attached to a
bracket on the platform hitch.
The Center High-Mounted Stoplamp (CHMSL) wire
is tied next to the trailer wiring harness for use with
a trailer.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
4-37
Other Service Items........................................5-66
Fuel Filter....................................................5-66
Primary Fuel Filter and Water Separator..........5-67
Secondary Fuel Filter and Water Separator/
Heater (Caterpillar
®Diesel)..........................5-68
Automatic Ether Injection System
(Caterpillar
®Diesel)....................................5-68
Front Wheel Bearings with Oil-Filled Hubs........5-69
Air Conditioning System.................................5-70
Tires..............................................................5-70
Inflation - Tire Pressure.................................5-71
Wheel Loading.............................................5-71
Dual Tire Operation.......................................5-72
When It Is Time for New Tires.......................5-72
Wheel Alignment and Tire Balance..................5-73
Tightening the Wheel Nuts.............................5-73
Wheel Replacement......................................5-77
If a Tire Goes Flat........................................5-78
Appearance Care............................................5-79
Cleaning the Inside of Your Vehicle.................5-80
Fabric/Carpet...............................................5-81
Instrument Panel, Vinyl, and Other
Plastic Surfaces........................................5-82
Care of Safety Belts......................................5-82
Weatherstrips...............................................5-82Washing Your Vehicle...................................5-83
Cleaning Exterior Lamps/Lenses.....................5-83
Finish Care..................................................5-83
Windshield and Wiper Blades.........................5-84
Aluminum or Chrome-Plated Wheels................5-84
Tires...........................................................5-85
Sheet Metal Damage.....................................5-85
Finish Damage.............................................5-85
Underbody Maintenance................................5-85
Chemical Paint Spotting.................................5-85
Vehicle Identi cation......................................5-87
Vehicle Identification Number (VIN).................5-87
Service Statement.........................................5-87
Service Parts Identification Label.....................5-88
Electrical System............................................5-88
Add-On Electrical Equipment..........................5-88
Headlamp Wiring..........................................5-88
Windshield Wiper Fuses................................5-88
Fusible Links................................................5-89
Power Windows and Other Power Options.......5-89
Fuses and Circuit Breakers............................5-89
Instrument Panel Fuse Block..........................5-89
Underhood Fuse Block..................................5-92
Capacities and Speci cations..........................5-95
Normal Maintenance Replacement Parts.........5-100
Section 5 Service and Appearance Care
5-2