Page 414 of 472
Fuses Usage
6 Driver Side Low-Beam Headlamp
7 Windshield Wiper
8 Automatic Transfer Case
9 Windshield Washer
10 Powertrain Control Module B
11 Fog Lamps
12 Stoplamp
13 Cigarette Lighter
14 Ignition Coils
15Transmission Control Module
Canister Vent
16 Truck Body Controller, Ignition 1
17 Crank
18 Airbag
19 Trailer Electric BrakeFuses Usage
20 Cooling Fan
21 Horn
22 Ignition E
23 Electronic Throttle Control
24Instrument Panel Cluster, Driver
Information Center
25Automatic Shift Lock Control
System
26 Engine 1
27 Backup
28 Powertrain Control Module 1
29 Powertrain Control Module
30 Air Conditioning
31 Injector Bank A
32 Trailer
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Page 415 of 472
Fuses Usage
33 Antilock Brakes (ABS)
34 Ignition A
35 Blower Motor
36 Ignition B
50 Passenger Side Trailer Turn
51 Driver Side Trailer Turn
52 Hazard Flashers
53 Transmission
54 Oxygen Sensor Bank B
55 Oxygen Sensor Bank A
56 Injector Bank B
57 Headlamp Driver Module
58 Body Controller 1
59 Electric Adjustable Pedal
61Vehicle Stability Enhancement
System (StabiliTrak
®)
62 Regulated Voltage Control
Relays Usage
37 Headlamp Washer
38 Rear Window Wiper
39 Fog Lamps
40 Horn
41 Fuel Pump
42 Windshield Washer
43 High-Beam Headlamp
44 Air Conditioning
45 Cooling Fan
46 Headlamp Driver Module
47 Starter
49 Electric Adjustable Pedal
60 Powertrain
Miscellaneous Usage
48 Instrument Panel Battery
5-117
Page 416 of 472
Rear Underseat Fuse Block
5-118
Page 417 of 472
Fuses Usage
01 Passenger Door Control Module
02 Driver Door Control Module
03 Liftgate Module 2
04 Truck Body Controller 3
05 Rear Fog Lamps
06 Blank
07 Truck Body Controller 2
08 Power Seats
09 Rear Wiper
10 Driver Door Module
11 Ampli er
12 Passenger Door Module
13 Rear Climate Controls
14 Driver Side Rear Parking Lamps
15 BlankFuses Usage
16Vehicle Center High-Mounted
Stoplamp (CHMSL)
17Passenger Side Rear Parking
Lamps
18 Locks
19Liftgate Module/Driver Seat
Module
20 Blank
21 Lock
23 Blank
24 Unlock
25 Blank
26 Blank
27OnStar
®Overhead Battery,
OnStar®System
28 Sunroof
5-119
Page 428 of 472

(e)Make sure the safety belt reminder light and safety
belt assemblies 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 see Checking
the Restraint Systems on page 1-66.
(f)Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
rear compartment hinges, outer liftgate handle pivot
points, rear door detent link, roller mechanism,
liftgate handle pivot points, latch bolt, fuel door hinge,
cargo 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.
(g)Inspect hoses for cracks, chafing, leaks, kinks,
and proper installation.(h)Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police, or delivery
service.
(i)Drain, flush, and refill cooling system. This service
can be complex; you should have your dealer/retailer
perform this service. See Engine Coolant on page 5-28
for what to use. Inspect hoses. Clean radiator,
condenser, pressure cap, and filler neck. Pressure test
the cooling system and pressure cap.
(j)A fluid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the fluid level checked. Add fluid if needed.
(k)If you drive regularly under dusty conditions, inspect
the filter at each engine oil change.
(l)Visually inspect belt for fraying, excessive cracks, or
obvious damage. Replace belt if necessary.
6-8
Page 430 of 472

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. SeeParking Brake on page 2-32.
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 vehicle
should start only in PARK (P) or NEUTRAL (N).
If the vehicle starts in any other position, contact
your dealer/retailer for service.
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. SeeParking Brake
on page 2-32.
Be ready to apply the regular brake immediately if
the vehicle begins to move.
3. With the engine off, turn the ignition to ON/RUN,
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 dealer/retailer
for service.
6-10
Page 431 of 472

Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition to LOCK/OFF in each shift lever position.
The ignition should turn to LOCK/OFF only
when the shift lever is in PARK (P).
The ignition key should come out only in
LOCK/OFF.
Contact your dealer/retailer if service is required.
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 the 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 dealer/retailer 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.
6-11
Page 433 of 472

Usage Fluid/Lubricant
Windshield
WasherOptikleen
®Washer Solvent.
Parking Brake
Cable GuidesChassis Lubricant
(GM Part No. U.S. 12377985,
in Canada 88901242) or lubricant
meeting requirements of NLGI #2,
Category LB or GC-LB.
Power Steering
SystemGM Power Steering Fluid
(GM Part No. U.S. 89021184,
in Canada 89021186).
Automatic
TransmissionDEXRON
®-VI Automatic
Transmission Fluid.
Key Lock
CylindersMulti-Purpose Lubricant, Superlube
(GM Part No. U.S. 12346241,
in Canada 10953474).
Chassis
LubricationChassis Lubricant
(GM Part No. U.S. 12377985,
in Canada 88901242) or lubricant
meeting requirements of NLGI #2,
Category LB or GC-LB.
Usage Fluid/Lubricant
Front AxleSAE 75W-90 Synthetic
Axle Lubricant
(GM Part No. U.S. 89021677,
in Canada 89021678) meeting
GM Speci cation 9986115.
Rear Axle
(Except
SS Model)SAE 75W-90 Synthetic
Axle Lubricant
(GM Part No. U.S. 89021677,
in Canada 89021678) meeting
GM Speci cation 9986115.
Rear Axle
(SS Model)SAE 75W-90 Synthetic
Axle Lubricant
(GM Part No. U.S. 89021677,
in Canada 89021678) meeting
GM Speci cation 9986115.
With a complete drain and re ll
add 5.5 ounces (163 ml) of
Limited-Slip Axle Lubricant Additive
(GM Part No. U.S. 1052358,
in Canada 992694) where required.
SeeRear Axle on page 5-49.
6-13