Page 403 of 452

*1Ð Gasoline Engine and Diesel Engine.
*2Ð Gasoline Engine; ECMRPV Ð Diesel Engine.
*3Ð Gasoline Engine; FUEL HT Ð Diesel Engine.
*4Ð Gasoline Engine; ECM I Ð Diesel Engine.
*5Ð IGN/EDU
Fuses Usage
GLOW PLUGDiesel Glow Plugs and Intake
Air Heater
CUST FEED Gasoline Accessory Power
STUD #1Auxiliary Power (Single
Battery and Diesels Only)/
Dual Battery (TP2) Do not
install fuse.
MBECMid Bussed Electrical Center
Power Feed, Front Seats,
Right Doors
BLOWER Front Climate Control Fan
LBECLeft Bussed Electrical
Center, Door Modules,
Door Locks, Auxiliary Power
Outlet Ð Rear Cargo Area
and Instrument Panel
Fuses Usage
STUD 2Accessory Power/Trailer
Wiring Brake Feed
ABS Anti-Lock Brakes
VSES/ECAS Vehicle Stability
IGN A Ignition Power
IGN B Ignition Power
LBEC 1Left Bussed Electrical Center,
Left Doors, Truck Body
Controller, Flasher Module
TRL PARK Parking Lamps Trailer Wiring
RR PARKRight Rear Parking and
Sidemarker Lamps
LR PARKLeft Rear Parking and
Sidemarker Lamps
PARK LP Parking Lamps Relay
STARTER Starter Relay
INTPARK Interior Lamps
STOP LP Stoplamps
5-111
Page 404 of 452
Fuses Usage
TBC BATTTruck Body Controller
Battery Feed
SUNROOF Sunroof
SEO B2 Off-Road Lamps
4WSVent Solenoid
Canister/Quadrasteer
Module Power
RR HVAC Not Used
AUX PWRAuxiliary Power
Outlet Ð Console
IGN 1 Ignition Relay
PCM 1 Powertrain Control Module
ETC/ECMElectronic Throttle Control,
Electronic Brake Controller
IGN EInstrument Panel Cluster,
Air Conditioning Relay,
Turn Signal/Hazard Switch,
Starter Relay
RTD Ride Control
TRL B/U Backup Lamps Trailer WiringFuses Usage
PCM BPowertrain Control Module,
Fuel Pump
F/PMP Fuel Pump (Relay)
B/U LPBack-up Lamps, Automatic
Transmission Shift Lock
Control System
RR DEFOG Rear Window Defogger
HDLP-HI Headlamp High Beam Relay
PRIME Not Used
02B Oxygen Sensors
SIRSupplemental In¯atable
Restraint System
FRT PARKFront Parking Lamps,
Sidemarker Lamps
DRLDaytime Running
Lamps (Relay)
SEO IGN Rear Defog Relay
TBC IGN1 Truck Body Controller Ignition
HI HDLP - LT High Beam Headlamp - Left
5-112
Page 405 of 452
Fuses Usage
LH HID Not Used
DRL Daytime Running Lamps
IPC/DICInstrument Panel
Cluster/Driver Information
Center
HVAC/ECAS Climate Control Controller
CIG LTR Cigarette Lighter
HI HDLP - RT High Beam Headlamp - Right
HDLP-LOW Headlamp Low Beam Relay
A/C COMP Air Conditioning Compressor
A/C COMPAir Conditioning Compressor
Relay
RR WPR Not Used
RADIO Audio System
SEO B1Mid Bussed Electrical Center,
Rear Heated Seats,
HomeLink
LO HDLP - LT Headlamp Low Beam - LeftFuses Usage
BTSIBrake Transmission Shift
Interlock System
CRANK Starting System
LO HDLP - RT Headlamp Low Beam - Right
FOG LP Fog Lamp Relay
FOG LP Fog Lamps
HORN Horn Relay
W/S WASHWindshield Washer
Pump Relay
W/S WASH Windshield Washer Pump
INFOOnStar/Rear Seat
Entertainment
RADIO AMP Radio Ampli®er
RH HID Not Used
HORN Horn
EAP Not Used
TREC All-Wheel Drive Module
SBA Supplemental Brake Assist
5-113
Page 411 of 452

Scheduled Maintenance
Service MaintenanceIMaintenanceII
Change engine oil and ®lter. Reset oil life system. See
Engine Oil on
page 5-11.An Emission Control Service.··
Lubricate chassis components.
See footnote #.··
Visually check for any leaks or damage.
See footnote (j).··
Inspect engine air cleaner ®lter or change indicator (if equipped). If necessary,
replace ®lter. See
Engine Air Cleaner/Filter on page 5-16.An Emission Control
Service. See footnote ².··
Rotate tires and check in¯ation pressures and wear. See
Tires on page 5-59.··
Inspect brake system.
See footnote (a).··
Check engine coolant and windshield washer ¯uid levels and add ¯uid as
needed.··
Perform any needed additional services. See ªAdditional Required Servicesº in
this section.··
Inspect suspension and steering components.
See footnote (b).·
Inspect engine cooling system.
See footnote (c).·
Inspect wiper blades.
See footnote (d).·
Inspect restraint system components.
See footnote (e).·
Lubricate body components.
See footnote (f).·
Check transmission ¯uid level and add ¯uid as needed.·
6-5
Page 414 of 452

Maintenance Footnotes
²The U.S. Environmental Protection Agency or the
California Air Resources Board has determined that the
failure to perform this maintenance item will not nullify
the emission warranty or limit recall liability prior to
the completion of the vehicle's useful life. We, however,
urge that all recommended maintenance services be
performed at the indicated intervals and the
maintenance be recorded.
#Lubricate the front suspension, ball joints, steering
linkage, transmission shift linkage and parking
brake cable guides. Ball joints should not be lubricated
unless their temperature is 10ÉF (-12ÉC) or higher,
or they could be damaged.
(a)Visually inspect brake lines and hoses for proper
hook-up, binding, leaks, cracks, cha®ng, etc. Inspect
disc brake pads for wear and rotors for surface
condition. Inspect other brake parts, including calipers,
parking brake, etc.
(b)Visually inspect front and rear suspension and
steering system for damaged, loose or missing parts,
signs of wear or lack of lubrication. Inspect power
steering lines and hoses for proper hook-up, binding,
leaks, cracks, cha®ng, etc. Visually check constant
velocity joints, rubber boots and axle seals for leaks.
(c)Visually inspect hoses and have them replaced if they
are cracked, swollen or deteriorated. Inspect all pipes,
®ttings and clamps; replace with genuine GM parts as
needed. To help ensure proper operation, a pressure test
of the cooling system and pressure cap and cleaning the
outside of the radiator and air conditioning condenser is
recommended at least once a year.
(d)Visually inspect wiper blades for wear or cracking.
Replace blade inserts that appear worn or damaged
or that streak or miss areas of the windshield.
(e)Make sure the safety belt reminder light and all your
belts, buckles, latch plates, retractors and anchorages
are working properly. Look for any other loose or
damaged safety belt system parts. If you see anything
that might keep a safety belt system from doing its
job, have it repaired. Have any torn or frayed safety belts
replaced. Also look for any opened or broken air bag
coverings, and have them repaired or replaced. (The air
bag system does not need regular maintenance.)
(f)Lubricate all key lock cylinders, body door hinges,
hood latch assembly, secondary latch, pivots, spring
anchor, release pawl, tailgate hinges, tailgatelinkage,
tailgate handle pivot points, latch bolt, fuel door
hinge, locks and folding seat hardware. More frequent
lubrication may be required when exposed to a corrosive
environment. Applying silicone grease on weatherstrips
with a clean cloth will make them last longer, seal
better and not stick or squeak.
6-8
Page 416 of 452

Engine Coolant Level Check
Check the engine coolant level and add
DEX-COOLžcoolant mixture if necessary. SeeEngine
Coolant on page 5-21for further details.
Windshield Washer Fluid Level Check
Check the windshield washer ¯uid level in the windshield
washer tank and add the proper ¯uid if necessary.
At Least Once a Month
Tire In¯ation Check
Visually inspect your tires and make sure tires are
in¯ated to the correct pressures. Do not forget to check
your spare tire. See
Tires on page 5-59for further
details. Check to make sure the spare tire is stored
securely. Push, pull and then try to rotate or turn
the spare tire. If it moves, tighten it. See
Changing a
Flat Tire on page 5-76.
At Least Once a Year
Starter Switch Check
{CAUTION:
When you are doing this inspection, the
vehicle could move suddenly. If the vehicle
moves, you or others could be injured.
1. Before you start, be sure you have enough room
around the vehicle.
2. Firmly apply both the parking brake and the regular
brake. See
Parking Brake on page 2-25if
necessary.
Do not use the accelerator pedal, and be ready to
turn off the engine immediately if it starts.
3. Try to start the engine in each gear. The starter
should work only in PARK (P) or NEUTRAL (N).
If the starter works in any other position, contact
your GM Goodwrench dealer for service.
6-10
Page 417 of 452

Automatic Transmission Shift Lock
Control System Check
{CAUTION:
When you are doing this inspection, the
vehicle could move suddenly. If the vehicle
moves, you or others could be injured.
1. Before you start, be sure you have enough room
around the vehicle. It should be parked on a level
surface.
2. Firmly apply the parking brake. See
Parking Brake
on page 2-25if necessary.
Be ready to apply the regular brake immediately if
the vehicle begins to move.3. With the engine off, turn the key to the RUN
position, but do not start the engine. Without
applying the regular brake, try to move the shift
lever out of PARK (P) with normal effort. If the shift
lever moves out of PARK (P), contact your GM
Goodwrench dealer for service.
Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition key to LOCK in each shift lever position.
·The key should turn to LOCK only when the
shift lever is in PARK (P).
·The key should come out only in LOCK.
Contact your GM Goodwrench dealer if service is
required.
6-11
Page 418 of 452

Parking Brake and Automatic
Transmission Park (P) Mechanism Check
{CAUTION:
When you are doing this check, your vehicle
could begin to move. You or others could be
injured and property could be damaged. Make
sure there is room in front of your vehicle in
case it begins to roll. Be ready to apply the
regular brake at once should the vehicle begin
to move.Park on a fairly steep hill, with the vehicle facing
downhill. Keeping your foot on the regular brake, set the
parking brake.
·To check the parking brake's holding ability: With
the engine running and transmission in
NEUTRAL (N), slowly remove foot pressure from
the regular brake pedal. Do this until the vehicle is
held by the parking brake only.
·To check the PARK (P) mechanism's holding ability:
With the engine running, shift to PARK (P). Then
release the parking brake followed by the regular
brake.
Contact your GM Goodwrench dealer if service is
required.
Underbody Flushing Service
At least every spring, use plain water to ¯ush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other debris
can collect.
6-12