Page 400 of 452
Fuses Usage
32 Trailer
33 Anti-lock Brakes (ABS)
34 Ignition A
35 Blower Motor
36 Ignition B
50 Passenger’s Side Trailer Turn
51 Driver’s Side Trailer Turn
52 Hazard Flashers
53 Headlamp Driver Module
54 Air Injection Reactor (AIR) Solenoid
56 Air Injection Reactor (AIR) Pump
Relays Usage
37 Blank or Headlamp Washer
38 Rear Window WasherFuses Usage
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
55 Air Injection Reactor (AIR) Solenoid
Miscellaneous Usage
48 Instrument Panel Battery
5-96
Page 402 of 452

Fuses Usage
1Electrically-Controlled Air
Suspension
2Passenger’s Side High-Beam
Headlamp
3Passenger’s Side Low-Beam
Headlamp
4 Back-Up-Trailer Lamps
5 Driver’s Side High-Beam Headlamp
6 Driver’s Side Low-Beam Headlamp
7 Rear Window Washer
8 Automatic Transfer Case
9 Windshield Washer
10 Powertrain Control Module B
11 Fog Lamps
12 Stoplamp
13 Cigarette Lighter
14 Ignition Coils
15 Canister Vent
16 Truck Body Controller, Ignition 1
17 Crank
18 Airbag
19 Trailer Electric Brake
20 Cooling Fan
21 HornFuses Usage
22 Ignition E
23 Electronic Throttle Control
24Instrument Panel Cluster, Driver
Information Center
25 Automatic Shift Lock Control System
26 Engine 1
27 Back-Up
28 Powertrain Control Module 1
29 Powertrain
30 Air Conditioning
31 Injector Bank A
32 Trailer
33 Anti-lock Brakes (ABS)
34 Ignition A
35 Blower Motor
36 Ignition B
50 Passenger’s Side Trailer Turn
51 Driver’s 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
5-98
Page 405 of 452
Fuses Usage
25 Blank
26 Blank
27OnStar
®Overhead Battery, OnStar®
System
28 Sunroof
29 Rainsense™ Wipers
30 Parking Lamps
31 Truck Body Controller Accessory
32 Truck Body Controller 5
33 Front Wipers
34 Vehicle Stop
35 Transmission Control Module
36 Heat Ventilation Air Conditioning B
37 Front Parking Lamps
38 Left Turn Signal
Fuses Usage
39 Heat Ventilation Air Conditioning I
40 Truck Body Controller 4
41 Radio
42 Trailer Park
43 Right Turn Signal
44 Heat Ventilation Air Conditioning
45 Rear Fog Lamps
46 Auxiliary Power 1
47 Ignition 0
48 Four-Wheel Drive
49 Blank
50 Truck Body Controller Ignition
51 Brakes
52 Truck Body Controller Run
5-101
Page 418 of 452

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 2-25if
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.
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 2-25if necessary.
Be ready to apply the regular brake immediately if
the vehicle begins to move.
3. With the engine off, turn the ignition to 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 GM Goodwrench
®dealer
for service.
6-10
Page 419 of 452

Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition to LOCK in each shift lever position.
The ignition 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.
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.
6-11
Page 444 of 452

Fuses
Engine Compartment Fuse Block...................5-93
Fuses and Circuit Breakers...........................5-93
Rear Underseat Fuse Block..........................5-99
Windshield Wiper.........................................5-92
G
Gage
Check Gages Warning Light..........................3-41
Engine Coolant Temperature.........................3-34
Fuel..........................................................3-42
Oil Pressure...............................................3-38
Speedometer..............................................3-27
Tachometer.................................................3-27
Voltmeter Gage...........................................3-32
Garage Door Opener.......................................2-42
Gasoline
Octane........................................................ 5-5
Speci cations............................................... 5-5
Gate Ajar Light...............................................3-41
Glove Box.....................................................2-46
GM Mobility Reimbursement Program.................. 7-5
H
Hazard Warning Flashers................................... 3-6
Head Restraints............................................... 1-5Headlamps....................................................3-14
Automatic Headlamp System.........................3-15
Bulb Replacement.......................................5-48
Daytime Running Lamps...............................3-14
Electrical System.........................................5-92
Flash-to-Pass............................................... 3-8
Halogen Bulbs............................................5-48
Headlamps, Front Turn Signal, Sidemarker,
and Parking Lamps..................................5-49
High/Low Beam Changer................................ 3-8
Heated Seats................................................... 1-3
Heater...........................................................3-19
Highbeam On Light.........................................3-40
Highway Hypnosis...........................................4-35
Hill and Mountain Roads..................................4-36
HomeLink
®Transmitter....................................2-42
HomeLink®Transmitter, Programming................2-43
Hood
Checking Things Under................................5-10
Release.....................................................5-10
Horn............................................................... 3-6
How to Use This Manual...................................... ii
How to Wear Safety Belts Properly...................1-12
I
Ignition Positions.............................................2-19
Infants and Young Children, Restraints...............1-28
In ation -- Tire Pressure..................................5-59
6