
4. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the
engine cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches slightly above the FULL
COLD mark.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
Engine Coolant (Caterpillar Diesel
Engines)
If your vehicle has a Caterpillar®diesel engine, see the
Caterpillar®Diesel Engine Operation & Maintenance
Manual provided with your vehicle to find out what to add,
as well as when and how to service your cooling system.
Coolant Surge Tank Pressure Cap
The coolant surge tank pressure cap is located in
the engine compartment, on the driver’s side of the
vehicle.
Notice:Your vehicle’s surge tank pressure cap is
designed for use with medium-duty cooling systems
only. If the surge tank pressure cap is not tightly
installed, coolant loss and possible engine damage
may occur. Be sure the cap is properly and tightly
secured.
5-47

Fuse Usage
16 Airbag System
17 Exterior/Interior Lamps
18 Parking Brake
19 Accessory Power
20 Ignition 4
21 Sidemarker Lamps
22 Turn Signal/Backup Lamps
23 Transmission
24 Hydraulics/Air Brake
A Spare
B Spare
Fuse Usage
Blank Not Used
BRK Brake Warning Lamp
RT PRK Passenger Side Parking Lamps
Blank Not Used
Blank Not Used
LT PARK Driver Side Parking Lamps
RT REAR
TRN/STOPPassenger Side Rear Turn
Signal/Stoplamp
LT REAR
TRN/STOPDriver Side Rear Turn
Signal/Stoplamp
Fuse Usage
RADIO Radio
Blank Not Used
Blank Not Used
PWR WNDW Power Windows
Relay Usage
ECU/PTO*Engine Control Unit/Power Take-Off
*Diesel 7.8 Duramax
BRK LAMPC4/C5 Brake Lamps,
C6/C7/C8 Tractor/Trailer Wiring
DRL Daytime Running Lamps
IGN-4 Ignition
CHMSL Center High Mounted Stoplamp
MRK LTS Sidemarker and Clearance Lamps
HTD/MIRR Heated Mirrors
HTR Diesel Heated Fuel
RT TRN TRLR Passenger Side Trailer Turn Signal
Blank Not Used
LT TRN TRLR Driver Side Trailer Turn Signal
Blank Not Used
Blank Not Used
Blank Not Used
5-98

Fuse Usage
PCM-B Powertrain Control Module
TCM Transmissions (LF8)
ENG 4 Engine 4 (LMM/LF6/LF8)
ENG 2 Engine 2 (L18/LMM)
HTD FUEL Heated Fuel (LMM)
BLANK Not Used
BLANK Not Used
NOTE 3 Fan Relay (LMM), Emissions (L18)
A/C COMP Air Conditioning Compressor
ABS 1 Antilock Brake System 1
ABS 2 Antilock Brake System 2
ABS 3 Antilock Brake System 3
ENGINE Engine
E/A PUMP Electronic/Automatic Pump
HORN Horn
NOTE 2Fuel (L18/LMM), Electronic Control
Module (LF6)Fuse Usage
NOTE 4 Electronic Control Module (LF6)
STUD A Spare
STUD B Spare
Relay Usage
NOTE 1 LMM/L18 Fuel Pump Relay
IGN B RELAY Ignition Relay
STARTER
RELAYStarter Relay
HORN RELAY Horn Relay
IGN A RELAY Ignition Relay
PTO/ECU*
RELAYPower Take-Off/Engine Control Unit
(*Diesel 7.8L LF8)
REVERSE
RELAYReverse Relay
FAN RELAY Fan Relay (LMM)
5-100

(11)= Chassis Lubrication Service: Lubricate all grease
fittings in front suspension, front axle, and steering
linkage. Do not lubricate kingpin bushings with air
pressure equipment; instead, use a hand grease gun to
ensure complete purge and eliminate sealer cap
distortion. Front axle tie rod ends, both upper and lower
kingpin fittings, and both steering linkage relay rod ends
should be greased with the vehicle loaded on the ground
and wheels turned straight ahead, not with the vehicle on
a hoist. Apply kingpin bushing lubricant to both upper and
lower kingpin grease fittings until new lubricant purges
from between the upper shim pack and thrust bearing.
Lubricate transmission and shift linkage, hood latches
and hood hinges, parking brake lever pivot, clevis pins
and linkage, disc brake caliper rails, clutch linkage and
release bearing (if equipped), bearing pads, propshaft
universal joints, brake camshaft bracket, slack adjusters,
pedal shaft, clutch cross shaft, clutch pedal springs, and
clutch cable bushing at transmission. Lubricate
suspension, axle, and steering linkage more often when
operating under dusty or muddy conditions and in
excessive off-road use. Frequently power-washed
vehicles will require more frequent lubrication.(12)= Check steering system:
•Look for damaged, loose, or missing parts. Inspect
the steering linkage relay rod and tie rod ends for
looseness or lack of lubricant. Also look for
parts showing signs of wear or lack of lubrication.
Replace parts as needed. Also check steering gear
mounting bolts, pitman arm nut, gear housing
upper cover and side cover attaching bolts, steering
column mounting bolts and cardan joint clamp
bolts; tighten if necessary. See the service manual.
•Inspect power steering hoses, tubes, and fittings for
leaks. Hoses and lines must not be twisted, kinked,
or tightly bent. Make sure clips, clamps, supporting
tubes, and hoses are in place and properly secured.
•Check steering gear for leakage around pitman shaft
and housing. If leakage is evident (lubricant oozing
out, not just oily film), leak should be corrected
immediately.
(13)= Check front and rear suspension. Look for
damaged, loose, or missing parts or parts showing signs
of wear or lack of lubrication. Replace parts as
needed.
6-22

OnStar®(Isuzu 7.8L L6 Engine)
If your vehicle has OnStar and you subscribe to the
OnStar services, please refer to the OnStar Terms and
Conditions for information on data collection and use.
Navigation System (Isuzu
7.8L L6 Engine)
If your vehicle has a navigation system, use of the
system may result in the storage of destinations,
addresses, telephone numbers, and other trip
information. Refer to the navigation system operating
manual for information on stored data and for deletion
instructions.
Radio Frequency Identification
(RFID) (Isuzu 7.8L L6 Engine)
RFID technology is used in some vehicles for functions
such as tire pressure monitoring and ignition system
security, as well as in connection with conveniences
such as key fobs for remote door locking/unlocking and
starting, and in-vehicle transmitters for garage door
openers. RFID technology in GM vehicles does not use
or record personal information or link with any other
GM system containing personal information.
7-13

Audio System(s).............................................3-49
Automatic Transmission
Fluid..........................................................5-42
Operation...................................................2-27
B
Battery..........................................................5-61
Bench Seat, Split............................................. 1-6
Brake
Diesel Engine Exhaust.................................2-26
Emergencies................................................ 4-5
Exhaust Indicator Light.................................3-41
Trailer Hand Control Valve.............................. 4-6
Brake Fluid....................................................5-52
Brakes..........................................................5-52
Hydraulic Systems......................................... 4-4
Parking Brake Burnish Procedure...................2-43
System Warning Light..................................3-31
Braking........................................................... 4-4
Braking in Emergencies..................................... 4-5
Break-In, New Vehicle.....................................2-10
Bucket Seats................................................... 1-2
Bulb Replacement...........................................5-71
Buying New Tires...........................................5-79
C
California Perchlorate Materials
Requirements............................................... 5-4
California Proposition 65 Warning....................... 5-4
Capacities and Specifications..........................5-102
Carbon Monoxide...................................2-45, 4-17
Care of
Safety Belts................................................5-89
Center Console Storage Area...........................2-53
Change Fuel Filter Warning Light......................3-45
Charging System Light....................................3-29
Check
Engine Lamp..............................................3-36
Gages Warning Light...................................3-43
Checking Things Under the Hood......................5-22
Chemical Paint Spotting...................................5-93
Child Restraints
Child Restraint Systems...............................1-36
Infants and Young Children...........................1-32
Lower Anchors and Tethers for Children..........1-40
Older Children.............................................1-28
Securing a Child Restraint in a Rear
Outside Seat Position...............................1-40
Securing a Child Restraint in the Center
Front Seat Position...................................1-44
2

Child Restraints (cont.)
Securing a Child Restraint in the Center
Rear Seat Position...................................1-42
Securing a Child Restraint in the Right
Front Seat Position...................................1-44
Where to Put the Restraint...........................1-38
Chime Level Adjustment..................................3-58
Cigarette Lighter.............................................3-19
Cleaning
Aluminum or Chrome-Plated Wheels..............5-92
Exterior Lamps/Lenses.................................5-90
Fabric/Carpet..............................................5-88
Finish Care.................................................5-90
Instrument Panel, Vinyl, and Other
Plastic Surfaces.......................................5-89
Interior.......................................................5-87
Tires..........................................................5-92
Underbody Maintenance...............................5-93
Washing Your Vehicle...................................5-90
Weatherstrips..............................................5-89
Windshield and Wiper Blades........................5-91
Climate Control System...................................3-20
Outlet Adjustment........................................3-22
Rear Heating System...................................3-23
Clock, Setting.................................................3-48
Collision Damage Repair................................... 7-6
Control of a Vehicle.......................................... 4-3Coolant
Engine.......................................................5-47
Engine Temperature Gage............................3-34
Low Warning Light.......................................3-35
Surge Tank Pressure Cap.............................5-47
Cooling System..............................................5-43
Cruise Control................................................3-10
Customer Assistance Information
Customer Assistance for Text Telephone
(TTY) Users.............................................. 7-4
Customer Assistance Offices........................... 7-4
Customer Satisfaction Procedure..................... 7-2
GM Mobility Reimbursement Program............... 7-5
Reporting Safety Defects to General Motors........ 7-9
Reporting Safety Defects to the Canadian
Government.............................................. 7-9
Reporting Safety Defects to the
United States Government.......................... 7-9
Roadside Assistance Program......................... 7-5
Service Publications Ordering Information........7-10
D
Daytime Running Lamp...................................3-15
Daytime Running Lamps Indicator Light.............3-42
Defensive Driving............................................. 4-2
3

Reporting Safety Defects
Canadian Government................................... 7-9
General Motors............................................. 7-9
United States Government.............................. 7-9
Restraint System Check
Checking the Restraint Systems....................1-59
Replacing Restraint System Parts After a
Crash.....................................................1-60
Roadside
Assistance Program....................................... 7-5
Rocking Your Vehicle to Get it Out....................4-19
Routing, Engine Drive Belt..............................5-110
Running Out of Fuel........................................5-17
Running the Vehicle While Parked.....................2-50
S
Safety Belt Reminders.....................................3-26
Safety Belts
Care of ......................................................5-89
How to Wear Safety Belts Properly................1-16
Lap Belt .....................................................1-27
Lap-Shoulder Belt........................................1-24
Safety Belt Extender....................................1-28
Safety Belt Use During Pregnancy.................1-26
Safety Belts Are for Everyone.......................1-11
Safety Warnings and Symbols............................... ii
Scheduled Maintenance..................................... 6-5
Scheduled Maintenance Supplements.................. 6-4Seats
Air Suspension Seats.................................... 1-6
Bucket Seats................................................ 1-2
Rear Seat Operation....................................1-10
Split Bench Seat........................................... 1-6
Securing a Child Restraint
Center Front Seat Position............................1-44
Center Rear Seat Position............................1-42
Rear Outside Seat Position...........................1-40
Right Front Seat Position..............................1-44
Service........................................................... 5-3
Accessories and Modifications......................... 5-3
California Perchlorate Materials
Requirements............................................ 5-4
California Proposition 65 Warning.................... 5-4
Doing Your Own Work................................... 5-5
Engine Fan Breakage.................................... 5-6
Engine Soon Lamp......................................3-36
Publications Ordering Information...................7-10
Transmission Warning Light..........................3-30
Servicing Your Airbag-Equipped Vehicle..............1-58
Setting the Clock............................................3-48
Sheet Metal Damage.......................................5-93
Signals, Turn and Lane-Change.......................... 3-7
Sliding Rear Windows....................................... 2-9
Snow Plow....................................................4-22
Specifications, Capacities...............................5-102
Speedometer..................................................3-25
Split Bench Seat.............................................. 1-6
Starting Diesel Engine.....................................2-14
10