Page 310 of 411
6-43 Inflation -- Tire Pressure
The Certification/Tire label, which is on the rear edge of
the driver's door, shows the correct inflation pressures
for your tires when they're cold. ªColdº means your
vehicle has been sitting for at least three hours or driven
no more than 1 mile (1.6 km).
NOTICE:
Don't let anyone tell you that underinflation or
overinflation is all right. It's not. If your tires
don't have enough air (underinflation), you can
get the following:
Too much flexing
Too much heat
Tire overloading
Bad wear
Bad handling
Bad fuel economy
NOTICE: (Continued)
NOTICE: (Continued)
If your tires have too much air (overinflation),
you can get the following:
Unusual wear
Bad handling
Rough ride
Needless damage from road hazards
When to Check
Check your tires once a month or more. Also, check the
tire pressure of the spare tire.
Page 326 of 411

6-59
Underbody Maintenance
Chemicals used for ice and snow removal and dust
control can collect on the underbody. If these are not
removed, accelerated corrosion (rust) can occur on
the underbody parts such as fuel lines, frame, floor
pan and exhaust system even though they have
corrosion protection.
At least every spring, flush these materials from the
underbody with plain water. Clean any areas where mud
and other debris can collect. Dirt packed in closed areas
of the frame should be loosened before being flushed.
Your dealer or an underbody car washing system can
do this for you.
Chemical Paint Spotting
Some weather and atmospheric conditions can create a
chemical fallout. Airborne pollutants can fall upon and
attack painted surfaces on your vehicle. This damage
can take two forms: blotchy, ringlet
-shaped
discolorations, and small irregular dark spots etched
into the paint surface.
Although no defect in the paint job causes this, GM will
repair, at no charge to the owner, the surfaces of new
vehicles damaged by this fallout condition within
12 months or 12,000 miles (20 000 km) of purchase,
whichever occurs first.
Page 334 of 411
6-67
NAME CIRCUITS PROTECTED
ETC Electronic Throttle Control
RR BLOWER Rear Auxiliary Blower
Motor Relays
CNG Compressed Natural Gas
ENG
-I Heated O2 Sensors, Mass Air
Flow Sensor, Evap Canister Purge
Valve, Crankshaft Position Sensor,
Secondary Air Injection Relay
(Diesel), Water in Fuel Sensor
(Diesel), Fuel Heater (Diesel),
Glowplug Relay (Diesel),
Wastegate Solenoid (Diesel)
ECM
-I Ignition Coil, Camshaft Position
Sensor, VCM, Fuel Injectors,
Coil Driver
IGN
-E Air Conditioning Clutch Relay
SPARE Spare Fuse
SPARE Spare Fuse
SPARE Spare FuseNAME CIRCUITS PROTECTED
A/C Air Conditioning Clutch Relay
HORN Horn Relay, Underhood Lamp(s)
ECM
-B Fuel Pump Relay, VCM, PCM,
Fuel Pump and Engine Oil
Pressure Switch
SPARE Spare Fuse
SPARE Spare Fuse
AUX A Upfitter Provisions
AUX B Upfitter Provisions
A/C RELAY Air Conditioning
HORN RELAY Horn
A.I.R. RELAY Air
FUEL
PUMP RELAYFuel Pump
STARTER
RELAYStarter
ABS EXPORT
RELAYABS Export
Page 336 of 411
6-69
Capacities and Specifications
All capacities are approximate. When adding, be sure to fill to the appropriate level or as recommended in
this manual.
See refrigerant charge label under the hood for charge capacity information and requirements.
Engine Identification -- Gasoline Engines
Engine ªVORTECº 4300 ªVORTECº 5000 ªVORTECº 5700 ªVORTECº 8100
Type V6 V8 V8 V8
VIN Code W M R G
Fuel System CSFI
1CSFI1CSFI1MFI2
Spark
Plug Gap0.060 inches
(1.52 mm)0.060 inches
(1.52 mm)0.060 inches
(1.52 mm)0.060 inches
(1.52 mm)
Firing Order
1
-6-5-4-3-21-8-4-3-6-5-7-21-8-4-3-6-5-7-21-8-7-2-6-5-4-3
1Central Sequential Fuel Injection
2Sequential Fuel Injection
Page 338 of 411
6-71 Fuel Tank Capacity
TYPE QUANTITY MODEL TYPE
Standard Tank 31.0 U.S. gallons (117.3 L) Passenger and Cargo
Standard Tank 35.0 U.S. gallons (132.5 L) Cab and Chassis
Optional Tank* 55.0 U.S. gallons (208.1 L) Cab and Chassis
*159 inch wheelbase or 177 inch wheelbase only
Air Conditioning Refrigerant Capacity
If you do your own service work, you'll need the proper service manual. See ªDoing Your Own Service Workº in the
Index for additional information. It is recommended that service work on your air conditioning system be performed
by a qualified technician.
REFRIGERANT TYPE CAPACITY
R±134a 2.0 lbs. (0.91 kg)
Front
R±134a 3.5 lbs. (1.6 kg)
Front and Rear
Page 339 of 411

6-72
Normal Maintenance Replacement Parts
Replacement Parts
Replacement part numbers listed in this section are based on the latest information available at the time of printing,
and are subject to change. If a part listed in this manual is not the same as the part used in your vehicle when it was
built, or if you have any questions, please contact your GM dealer.
These specifications are for information only. If you have any questions, see the service manual for the chassis or
refer to the body manufacturer's publications.
EngineªVORTECº 4300
V6ªVORTECº 5000
V8ªVORTECº 5700
V8ªVORTECº8100
V8
VIN W M R G
Oil Filter PF47 PF1218 PF1218 PF454
Engine Air Cleaner Filter * A917C A917C A917C A917C
PCV Valve CV769C CV769C CV769C **
Spark Plugs
41
-932 41-932 41-932 TJ14R-P15
Fuel Filter GF481 GF481 GF481 GF481
Radiator Cap RC36 RC36 RC36 RC36
* Replace with ACDelco
Air Filter, Part No. A917C and for severe dusty conditions, use ACDelco Air Filter,
Part No. 1236C.
**8100 V8 has an internal PCV which does not require replacement.
Page 343 of 411

7-4
Part A: Scheduled
Maintenance Services
Using Your Maintenance Schedule
We at General Motors want to help you keep your
vehicle in good working condition. But we don't know
exactly how you'll drive it. You may drive very short
distances only a few times a week. Or you may drive
long distances all the time in very hot, dusty weather.
You may use your vehicle in making deliveries.
Or you may drive it to work, to do errands or in
many other ways.
Because of all the different ways people use their
vehicles, maintenance needs vary. You may need
more frequent checks and replacements. So please
read the following and note how you drive. If you
have any questions on how to keep your vehicle in
good condition, see your dealer.
This part tells you the maintenance services you should
have done and when you should schedule them. If you
go to your dealer for your service needs, you'll know
that GM
-trained and supported service people will
perform the work using genuine GM parts.The proper fluids and lubricants to use are listed in
Part D. Make sure whoever services your vehicle
uses these. All parts should be replaced and all
necessary repairs done before you or anyone else
drives the vehicle.
These schedules are for vehicles that:
carry passengers and cargo within recommended
limits. You will find these limits on your vehicle's
Certification/Tire label. See ªLoading Your Vehicleº
in the Index.
are driven on reasonable road surfaces within legal
driving limits.
use the recommended fuel. See ªFuelº in the Index.
Selecting the Right Schedule
First you'll need to decide which of the two schedules
is right for your vehicle. Here's how to decide which
schedule to follow:
Page 345 of 411

Scheduled Maintenance
7-6
Short Trip/City Intervals
Every 24,000 Miles (40 000 km): Diesel Engine Only:
Fuel Cap Replacement, if driving in dusty conditions.
Every 30,000 Miles (50 000 km): Diesel Engine
Only: Engine Air Cleaner Filter Replacement.
Fuel Filter Replacement.
Every 50,000 Miles (83 000 km): Automatic
Transmission Service (vehicles over 8600 GVWR
or driven under severe conditions or equipped with
diesel engine).
Every 60,000 Miles (100 000 km): Engine Accessory
Drive Belt Inspection. If Equipped: Exhaust Gas
Recirculation System Inspection. Gasoline Engine
Only: Evaporative Control System Inspection. Diesel
Engine Only: Crankcase Depression Regulator Valve
(CDRV) System Check.
Short Trip/City Intervals
Every 100,000 Miles (166 000 km): Gasoline Engine
Only: Spark Plug Wire Inspection. Gasoline Engine
Only: Spark Plug Replacement. Gasoline Engine
Only: Automatic Transmission Service (normal
conditions). Gasoline Engine Only (Except 8.1L V8):
Positive Crankcase Ventilation (PCV)
Valve Inspection.
Every 150,000 Miles (240 000 km): Cooling System
Service (or every 60 months, whichever occurs first).
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.