Page 417 of 470
Underhood Fuse BlockThe underhood fuse block in the engine compartment is
located on the driver’s side of the vehicle near the
battery. Lift the cover for access to the fuse/relay block.
To remove fuses if you don’t have a fuse extractor,
hold the end of the fuse between your thumb and index
nger and pull straight out.
SeeEngine Compartment Overview on page 5-12for
more information on its location.
5-111
Page 419 of 470

Fuses Usage
GLOW PLUG Not Used
CUST FEED Gasoline Accessory Power
HYBRID Hybrid
STUD #1Accessory Power/Trailer
Wiring
MBEC 1Mid Bussed Electrical Center
Power Feed, Front Seats,
Right Doors
BLOWER Front Climate Control Fan
LBEC 2Left Bussed Electrical
Center, Door Modules,
Door Locks, Auxiliary Power
Outlet — Rear Cargo Area
and Instrument Panel
STUD #2Accessory Power/Trailer
Wiring Brake Feed
ABS Anti-Lock Brakes
VSES/ECASElectronically Controlled
Air Suspension
IGN A Ignition Switch
IGN B Ignition SwitchFuses Usage
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
STRTR Starter Relay
INTPARK Roof Marker Lamps
STOP LP Stoplamps
TBC BATTTruck Body Controller
Battery Feed
S/ROOF Sunroof
SEO B2 Off-Road Lamps
4WS Vent Solenoid Canister
RR HVAC Not Used
AUX PWRAuxiliary Power
Outlet — Console
5-113
Page 420 of 470

Fuses Usage
IGN 1 PCM Ignition
PCM 1 Powertrain Control Module
ETC/ECMElectronic Throttle Control,
Electronic Brake Controller
INJ 1Ignition Coil, Fuel
Injectors - Bank 1
INJ 2Ignition Coil, Fuel
Injectors - Bank 2
IGN EInstrument Panel Cluster, Air
Conditioning Relay, Turn
Signal/Hazard Switch, Starter
Relay, Electronic Brake
Controller TC2 Mode Switch
RTDElectronic Brake Controller
Battery Feed
TRL B/U Backup Lamps Trailer Wiring
PCM BPowertrain Control Module,
Fuel Pump
F/PMP Fuel Pump (Relay)
02A Oxygen SensorsFuses Usage
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
O2B Oxygen Sensors
AIRBAGSupplemental 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
LH HID Not Used
DRL Daytime Running Lamps
RVC Regulated Voltage Control
5-114
Page 421 of 470
Fuses Usage
IPC/DICInstrument Panel Cluster/
Driver Information Center
HVAC/ECASClimate Control Controller/
Electronically Controlled
Air Suspension
CIG LTR Cigarette Lighter
HI HDLP - RT High Beam Headlamp - Right
HDLP - LOW Headlamp Low Beam Relay
A/C COMPAir Conditioning
Compressor Relay
A/C COMP Air Conditioning Compressor
RR WPR Rear Wiper/Washer
RADIO Audio System
SEO B1Mid Bussed Electrical
Center, HomeLink, Rear
Heated Seats
LO HDLP - LT Headlamp Low Beam - Left
BTSIBrake Transmission Shift
Interlock SystemFuses Usage
CRNK Starting System
LO HDLP-RT Headlamp Low Beam-Right
FOG LP Not Used
FOG LP Not Used
HORN Horn Relay
W/S WASHWindshield and Rear Window
Washer Pump Relay
W/S WASHWindshield and Rear Window
Washer Pump
INFO OnStar
®
RADIO AMP Radio Ampli er
RH HID Not Used
HORN Horn
EAP Not Used
TREC All-Wheel Drive Module
SBA Not Used
5-115
Page 422 of 470
Auxiliary Electric Cooling Fan
Fuse Block
The auxiliary electric
cooling fan fuse block is
located in the engine
compartment on the
driver’s side of the vehicle
next to the underhood
fuse block.Lift the cover for access to the fuse/relay block.
Fuses Usage
COOL/FAN Cooling Fan
COOL/FAN Cooling Fan Relay Fuse
COOL/FAN Cooling Fan Fuse
Relays Usage
COOL/FAN 1 Cooling Fan Relay 1
COOL/FAN 3 Cooling Fan Relay 3
COOL/FAN 2 Cooling Fan Relay 2
5-116
Page 433 of 470

(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 airbag
coverings, and have them repaired or replaced.
The airbag system does not need regular maintenance.(f)Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
rear compartment hinges, outer tailgate handle
pivot points, latch bolt, fuel door hinge, 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 system. Check all fuel and vapor lines and
hoses for proper hook-up, routing, and condition. Check
that the purge valve works properly, if equipped.
Replace as needed.
(h)Change automatic transmission uid and lter 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.
6-9
Page 436 of 470

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 2-25.
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.
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.
6-12
Page 438 of 470