
Repeat this until help arrives but only when you feel
really uncomfortable from the cold. Moving about
to keep warm also helps.
If it takes some time for help to arrive, now and then
when you run the engine, push the accelerator
pedal slightly so the engine runs faster than the idle
speed. This keeps the battery charged to restart
the vehicle and to signal for help with the headlamps.
Do this as little as possible to save fuel.
If Your Vehicle is Stuck in Sand,
Mud, Ice, or Snow
Slowly and cautiously spin the wheels to free the
vehicle when stuck in sand, mud, ice, or snow. See
Rocking Your Vehicle to Get It Out on page 4-19.
If the vehicle has a traction system, it can often help to
free a stuck vehicle. Refer to the vehicle’s traction
system in the Index. If stuck too severely for the traction
system to free the vehicle, turn the traction system off
and use the rocking method.
{CAUTION:
If you let your vehicle’s tires spin at high speed,
they can explode, and you or others could be
injured. The vehicle can overheat, causing an
engine compartment fire or other damage. Spin the
wheels as little as possible and avoid going above
35 mph (55 km/h) as shown on the speedometer.
Rocking Your Vehicle to Get It Out
Turn the steering wheel left and right to clear the area
around the front wheels. For four-wheel-drive vehicles,
shift into 4HI. Turn off any traction system. Shift back and
forth between R (Reverse) and a forward gear, or with a
manual transmission, between 1 (First) or 2 (Second) and
R (Reverse), spinning the wheels as little as possible.
To prevent transmission wear, wait until the wheels stop
spinning before shifting gears. Release the accelerator
pedal while shifting, and press lightly on the accelerator
pedal when the transmission is in gear. Slowly spinning
the wheels in the forward and reverse directions causes a
rocking motion that could free the vehicle. If that does not
get the vehicle out after a few tries, it might need to be
towed out. If the vehicle does need to be towed out, see
Towing Your Vehicle on page 4-23.
4-19

Towing
Towing Your Vehicle
Consult your dealer/retailer or a professional towing
service to have the vehicle towed. They can provide the
right equipment and know-how to tow it without
damage. SeeRoadside Assistance Program on
page 7-5.
Releasing Air-Operated Parking Brakes
If the vehicle has air brakes, there could be a special
towing problem. If the vehicle has to be towed because
of a complete loss of air pressure from both systems,
the parking brakes will have automatically engaged.The tow operator can release the brakes manually by
using the following steps. Then the vehicle can be towed
with all wheels or only the rear wheels on the ground.
1. Block the wheels of the vehicle.
2. Remove the release stud and nut from the side of
the brake chamber. Some chambers have studs
which are visible at all times.
4-23

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.........................5-5
Engine Fan Breakage.....................................5-6
Fuel................................................................5-6
Gasoline Octane............................................5-6
Gasoline Specifications....................................5-7
Additives.......................................................5-7
Diesel Engine Fuel.........................................5-8
What Fuel to Use...........................................5-8
Very Cold Weather Operation.........................5-11
Water in Fuel...............................................5-11
Running Out of Fuel.....................................5-17
Fuel Filter Replacement.................................5-18
Fuels in Foreign Countries.............................5-19
Filling the Tank............................................5-20
Filling a Portable Fuel Container.....................5-22
Checking Things Under the Hood....................5-22
Hood Latches...............................................5-23
Engine Oil (DURAMAX Diesel Engine).............5-24
Engine Oil (Caterpillar Diesel Engine)..............5-27
Engine Oil (Isuzu Diesel Engine).....................5-28
Engine Oil (Gasoline Engine)..........................5-32
Engine Oil Life System (Gasoline Engine)........5-35Engine Oil Life System (DURAMAX/Isuzu
Diesel Engines).........................................5-36
Engine Oil Life System (Caterpillar
Diesel Engine)..........................................5-38
Engine Air Cleaner/Filter................................5-38
Automatic Transmission Fluid.........................5-42
Manual Transmission Fluid.............................5-42
Cooling System............................................5-43
Engine Coolant (Caterpillar Diesel Engines)......5-47
Coolant Surge Tank Pressure Cap..................5-47
Engine Overheating.......................................5-48
Engine Fan Noise.........................................5-49
Power Steering Fluid.....................................5-49
Windshield Washer Fluid................................5-50
Brakes........................................................5-52
Battery........................................................5-61
Jump Starting...............................................5-62
Rear Axle.......................................................5-67
Rear Axle Shift Motor....................................5-68
Four-Wheel Drive............................................5-68
Front Axle......................................................5-69
Noise Control System.....................................5-70
Tampering with Noise Control System
Prohibited.................................................5-70
Bulb Replacement..........................................5-71
Section 5 Service and Appearance Care
5-1

Windshield Wiper Blade Replacement..............5-71
Other Service Items........................................5-72
Fuel Filter....................................................5-72
Primary Fuel Filter and Water Separator..........5-73
Secondary Fuel Filter and Water Separator/
Heater (Caterpillar Diesel)............................5-74
Front Wheel Bearings with
Oil-Filled Hubs..........................................5-75
Tires..............................................................5-76
Inflation - Tire Pressure.................................5-77
Wheel Loading.............................................5-78
Dual Tire Operation.......................................5-78
When It Is Time for New Tires.......................5-78
Buying New Tires.........................................5-79
Wheel Alignment and Tire Balance..................5-80
Tightening the Wheel Nuts.............................5-80
Wheel Replacement......................................5-84
If a Tire Goes Flat........................................5-85
Appearance Care............................................5-87
Interior Cleaning...........................................5-87
Fabric/Carpet...............................................5-88
Instrument Panel, Vinyl, and Other
Plastic Surfaces........................................5-89
Care of Safety Belts......................................5-89
Weatherstrips...............................................5-89
Washing Your Vehicle...................................5-90Cleaning Exterior Lamps/Lenses.....................5-90
Finish Care..................................................5-90
Windshield and Wiper Blades.........................5-91
Aluminum or Chrome-Plated Wheels
and Trim..................................................5-92
Tires...........................................................5-92
Sheet Metal Damage.....................................5-93
Finish Damage.............................................5-93
Underbody Maintenance................................5-93
Chemical Paint Spotting.................................5-93
Vehicle Identification
......................................5-94
Vehicle Identification Number (VIN).................5-94
Service Parts Identification Label.....................5-94
Electrical System............................................5-95
Add-On Electrical Equipment..........................5-95
Headlamp Wiring..........................................5-95
Windshield Wiper Fuses................................5-95
Fusible Links................................................5-95
Power Windows and Other Power Options..........5-96
Fuses and Circuit Breakers............................5-96
Instrument Panel Fuse Block..........................5-96
Underhood Fuse Block..................................5-99
Capacities and Specifications........................5-102
Normal Maintenance Replacement Parts.........5-108
Maintenance Replacement Parts...................5-108
Engine Drive Belt Routing............................5-110
Section 5 Service and Appearance Care
5-2

Hood Latches
To tilt the hood forward, pull back and up on each of the
hood latches, located above the wheel wells on both
sides of the vehicle.Then take the hand hold and pull the hood forward.
When you tilt the hood far enough, there are cables that
will support it. When you close the hood, make sure
both latches are secured.
5-23

Four-Wheel Disc Brakes
(Hydraulic Only)
The vehicle has four-wheel disc brakes.
Some driving conditions or climates can cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
the brakes.
Brake linings should always be replaced as complete
axle sets.
Four-Wheel and Six-Wheel Drum
Brakes (Air Only)
The brake drums should be removed and inspected
each time the tires are removed for rotation or changing.
When the front brakes are replaced, have the rear
brakes inspected, too.
Brake linings should always be replaced as complete
axle sets.
Brake Pedal Travel
See your dealer/retailer if the brake pedal does not
return to normal height, or if there is a rapid increase in
pedal travel. This could be a sign that brake service
might be required.
Brake Adjustment
Every brake stop, the brakes adjust for wear.
Brake Adjustment on Air Braked Vehicles
The vehicle has automatic slack adjusters. Every
brake stop, the brakes automatically adjust for wear.
Slack adjusters should never be manually adjusted
to correct excessive brake chamber pushrod stroke.
Excessive brake chamber pushrod stroke means
that the brake system needs to be serviced by a
qualified service technician.
Notice:Do not manually adjust automatic slack
adjusters. Manual adjustment of the automatic slack
adjusters can result in a degradation of the slack
adjuster performance over time. If the brake
chamber pushrod stroke is out of adjustment, the
brake system needs to be serviced by a qualified
service technician.
5-54

Item Number Item Remarks
4 Pivot Points and Hinges Apply chassis lubricant.
5 Pivot Points and Hinges Apply chassis lubricant.
6 Slack Adjuster** One fitting.
7Brake Cam Roller Pins at interface of pin
and shoe**Apply engine oil.
8 Front Steering KnucklesOne fitting each side, lower bushing.
(Hand-operated grease gun only.) Hand-pack upper
bearing.
9 Front Wheel Bearings Hand-pack or lubricate.
10 Steering Tie Rod Ends One fitting each end.
11 Spring Slip Pads* (Multi-Leaf Only) Apply chassis lubricant.
12 Clutch Release Bearing* Cup or fitting.
13 Battery Terminal (except “ST” type) Keep coated with petroleum jelly.
14 Transmission Fill to level of filler plug.
15 Propshaft U-JointsLubricate with GM Part No. 1051344 Wheel Bearing
Lubricant.
16 Parking Brake Clevis Pin$ Apply chassis lubricant.
17 Parking Brake Lever Pivot*, $ Apply chassis lubricant.
18Clutch Release Cross Shaft, Master
Cylinder$Apply chassis lubricant, fill to 1/4 inch (6 mm) below
opening.
19 Release Bearing, Clutch Cross Shaft Two fittings, apply chassis lubricant.
20 Clutch Release Fork Two fittings.
* Applies to some vehicles.
** Applies to air brakes only.
$ Applies to hydraulic brakes only.
5-59

Tandem Axle ModelsItem
Number Item Remarks
1 Brake Camshafts One fitting each.
2 Propshaft U-JointOne fitting
each joint.
Lubricate with GM
Part No. 1051344,
Wheel Bearing
Lubricant.
3 Rear AxlesFill to level of
filler plug.
4Brake Shoe
Roller PinsApply engine oil
at pin to shoe
joint only.
5 Rear Spring PinOne fitting
each side.
5-60