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Driving On Grades
Reduce speed and shift to a lower gearbeforestarting
down a long or steep downgrade. If the transmission is
not shifted down, the brakes might have to be used so
much that they would get hot and no longer work well.
The vehicle can tow in D (Drive). Shift the transmission
to a lower gear if the transmission shifts too often
under heavy loads and/or hilly conditions.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes. If the engine is
turned off immediately after towing at high altitude on
steep uphill grades, the vehicle may show signs similar to
engine overheating. To avoid this, let the engine run while
parked, preferably on level ground, with the automatic
transmission in P (Park) for a few minutes before turning
the engine off. If the overheat warning comes on, see
Engine Overheating on page 5-31.
Parking on Hills
{CAUTION:
Parking the vehicle on a hill with the trailer attached
can be dangerous. If something goes wrong, the rig
could start to move. People can be injured, and
both the vehicle and the trailer can be damaged.
When possible, always park the rig on a flat
surface.
If parking the rig on a hill:
1. Press the brake pedal, but do not shift into P (Park)
yet for vehicles with an automatic transmission, or
into gear for vehicles with a manual transmission.
Turn the wheels into the curb if facing downhill or into
traffic if facing uphill.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
brake pedal until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking
brake and shift into P (Park) for vehicles with an
automatic transmission or into gear for vehicles with
a manual transmission.
5. Release the brake pedal.
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Leaving After Parking on a Hill
1. Apply and hold the brake pedal while you:
•start the engine,
•shift into a gear, and
•release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
The vehicle needs service more often when pulling a
trailer. See this manual’s Maintenance Schedule
or Index for more information. Things that are especially
important in trailer operation are automatic transmission
fluid, engine oil, axle lubricant, belts, cooling system
and brake system. It is a good idea to inspect
these before and during the trip.
Check periodically to see that all hitch nuts and bolts
are tight.
Trailer Wiring Harness
The optional heavy-duty trailer wiring package includes
a wiring harness, with a seven-pin connector at the
rear of the vehicle and a four-wire harness assembly
under the driver side of the instrument panel. The
four-wire harness assembly comes without a connector.
If the vehicle does not have a trailer hitch, the
seven-wire harness assembly with connector is taped
together and located in a frame pocket at the driver side
rear left corner of the frame.
If the vehicle has a trailer hitch, the seven-wire harness
assembly with connector is attached to a bracket on
the hitch platform. In both cases, the seven-wire harness
has a connector and includes a 30-amp feed wire.
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The seven-wire harness connector contains the following
trailer circuits:
•Light Green: Back-up Lamps (10A fuse)**
•White: Ground
•Dark Blue: Trailer Brake Signal
•Dark Green: Right Rear Stop and Turn Signal*
•Red/Black Stripe: Battery Feed (30A Fuse)
•Brown: Trailer Park Lamp Supply Voltage
(15A fuse)**
•Yellow: Left Rear Stop and Turn Signal *The four-wire harness (without connector) contains the
following circuits:
•Black: Ground
•Red/White: Battery Feed
•Dark Blue: Trailer Brake Signal
•Light Blue: CHMSL/Stoplamp Supply Voltage
* If the vehicle is a cutaway with trailer provisions, a
15 amp fuse will be shared for both left/stop trailer turn
and right/stop trailer turn signals. However, the cutaway
lighting connector will have a 10 amp fuse for each
signal.
** If the vehicle is a cutaway with trailer provisions,
a 15 amp fuse will be shared for trailer park lamps and
cutaway rear lighting connector park lamps. Also, a
10 amp fuse will be shared for trailer back-up lamps
and cutaway rear lighting connector back-up lamps.
4-41
Page 244 of 408
Page 245 of 408

Service............................................................5-3
Accessories and Modifications..........................5-3
California Proposition 65 Warning.....................5-4
California Perchlorate Materials Requirements.....5-4
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside of the
Vehicle......................................................5-5
Fuel................................................................5-5
Gasoline Octane............................................5-6
Gasoline Specifications....................................5-6
California Fuel...............................................5-6
Additives.......................................................5-7
Fuel E85 (85% Ethanol)..................................5-8
Fuels in Foreign Countries...............................5-9
Filling the Tank............................................5-10
Filling a Portable Fuel Container.....................5-12
Checking Things Under the Hood....................5-12
Hood Release..............................................5-13
Engine Compartment Overview.......................5-14
Engine Oil...................................................5-15
Engine Oil Life System..................................5-18
Engine Air Cleaner/Filter................................5-20
Automatic Transmission Fluid.........................5-21
Cooling System............................................5-24
Engine Coolant.............................................5-25Radiator Pressure Cap..................................5-31
Engine Overheating.......................................5-31
Engine Fan Noise.........................................5-33
Power Steering Fluid.....................................5-34
Windshield Washer Fluid................................5-35
Brakes........................................................5-36
Battery........................................................5-39
Jump Starting...............................................5-40
All-Wheel Drive..............................................5-44
Rear Axle
.......................................................5-45
Front Axle......................................................5-46
Noise Control System.....................................5-47
Tampering with Noise Control System
Prohibited.................................................5-47
Bulb Replacement..........................................5-48
Halogen Bulbs..............................................5-48
Headlamps..................................................5-48
Front Turn Signal, Sidemarker and
Parking Lamps..........................................5-50
Center High-Mounted Stoplamp (CHMSL).........5-51
Taillamps.....................................................5-51
Replacement Bulbs.......................................5-52
Windshield Wiper Blade Replacement..............5-53
Section 5 Service and Appearance Care
5-1
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Tires..............................................................5-54
Tire Sidewall Labeling...................................5-55
Tire Terminology and Definitions.....................5-59
Inflation - Tire Pressure.................................5-62
Dual Tire Operation.......................................5-63
Tire Pressure Monitor System.........................5-64
Tire Pressure Monitor Operation.....................5-65
Tire Inspection and Rotation...........................5-69
When It Is Time for New Tires.......................5-71
Buying New Tires.........................................5-72
Different Size Tires and Wheels......................5-73
Uniform Tire Quality Grading..........................5-74
Wheel Alignment and Tire Balance..................5-76
Wheel Replacement......................................5-76
Tire Chains..................................................5-78
If a Tire Goes Flat........................................5-79
Changing a Flat Tire.....................................5-80
Removing the Spare Tire and Tools................5-81
Removing the Flat Tire and Installing the
Spare Tire................................................5-84
Secondary Latch System...............................5-92
Storing a Flat or Spare Tire and Tools............5-95
Spare Tire...................................................5-96
Appearance Care............................................5-97
Interior Cleaning...........................................5-97
Fabric/Carpet...............................................5-98Instrument Panel, Vinyl, and Other Plastic
Surfaces..................................................5-99
Care of Safety Belts....................................5-100
Weatherstrips.............................................5-100
Washing Your Vehicle..................................5-100
Cleaning Exterior Lamps/Lenses....................5-101
Finish Care................................................5-101
Windshield and Wiper Blades.......................5-102
Aluminum Wheels.......................................5-102
Tires.........................................................5-103
Sheet Metal Damage...................................5-103
Finish Damage...........................................5-103
Underbody Maintenance...............................5-103
Chemical Paint Spotting...............................5-103
Vehicle Identi cation.....................................5-104
Vehicle Identification Number (VIN)................5-104
Service Parts Identification Label...................5-104
Electrical System..........................................5-105
Add-On Electrical Equipment.........................5-105
Headlamp Wiring........................................5-105
Windshield Wiper Fuses...............................5-105
Fuses and Circuit Breakers..........................5-105
Floor Console Fuse Block............................5-105
Engine Compartment Fuse Block...................5-107
Capacities and Speci cations........................5-111
Section 5 Service and Appearance Care
5-2
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Service
For service and parts needs, visit your dealer/retailer.
You will receive genuine GM parts and GM-trained and
supported service people.
Genuine GM parts have one of these marks:
Accessories and Modi cations
When non-dealer/non-retailer accessories are added
to the vehicle, they can affect vehicle performance and
safety, including such things as airbags, braking, stability,
ride and handling, emissions systems, aerodynamics,
durability, and electronic systems like antilock brakes,
traction control, and stability control. Some of these
accessories could even cause malfunction or damage
not covered by the vehicle warranty.
GM Accessories are designed to complement and
function with other systems on the vehicle. Your GM
dealer/retailer can accessorize the vehicle using genuine
GM Accessories. When you go to your GM dealer/retailer
and ask for GM Accessories, you will know that
GM-trained and supported service technicians will
perform the work using genuine GM Accessories.
Also, seeAdding Equipment to Your Airbag-Equipped
Vehicle on page 1-76.
5-3
Page 248 of 408

California Proposition 65 Warning
Most motor vehicles, including this one, contain and/or
emit chemicals known to the State of California to cause
cancer and birth defects or other reproductive harm.
Engine exhaust, many parts and systems (including
some inside the vehicle), many fluids, and some
component wear by-products contain and/or emit
these chemicals.
California Perchlorate Materials
Requirements
Certain types of automotive applications, such as
airbag initiators, seat belt pretensioners, and lithium
batteries contained in remote keyless transmitters,
may contain perchlorate materials. Special handling
may be necessary. For additional information, see
www.dtsc.ca.gov/hazardouswaste/perchlorate.
Doing Your Own Service Work
{CAUTION:
You can be injured and the vehicle could be
damaged if you try to do service work on a
vehicle without knowing enough about it.
•Be sure you have sufficient knowledge,
experience, the proper replacement parts,
and tools before attempting any vehicle
maintenance task.
•Be sure to use the proper nuts, bolts, and
other fasteners. English and metric fasteners
can be easily confused. If the wrong fasteners
are used, parts can later break or fall off.
You could be hurt.
5-4