Page 319 of 486
When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
·start your engine,
·shift into a gear, and
·release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you're
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission ¯uid (don't over®ll),
engine oil, axle lubricant, belts, cooling system and
brake system. Each of these is covered in this manual,
and the Index will help you ®nd them quickly. If
you're trailering, it's a good idea to review these sections
before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
4-63
Page 321 of 486

Service............................................................5-3
Doing Your Own Service Work.........................5-3
Adding Equipment to the Outside of Your
Vehicle......................................................5-4
Fuel................................................................5-4
Gasoline Octane............................................5-4
Gasoline Speci®cations....................................5-5
California Fuel...............................................5-5
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-6
Filling Your Tank............................................5-7
Filling a Portable Fuel Container.......................5-9
Checking Things Under
the Hood....................................................5-10
Hood Release..............................................5-10
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-14
Engine Air Cleaner/Filter................................5-19
Automatic Transmission Fluid.........................5-21
Engine Coolant.............................................5-24
Coolant Surge Tank Pressure Cap..................5-27
Engine Overheating.......................................5-28
Cooling System............................................5-30Engine Fan Noise.........................................5-36
Power Steering Fluid.....................................5-36
Windshield Washer Fluid................................5-38
Brakes........................................................5-39
Battery........................................................5-43
Jump Starting...............................................5-44
All-Wheel Drive..............................................5-50
Rear Axle.......................................................5-51
Front Axle......................................................5-52
Headlamp Aiming...........................................5-53
Headlamp Horizontal Aiming...........................5-54
Headlamp Vertical Aiming..............................5-55
Bulb Replacement..........................................5-57
High Intensity Discharge (HID) Lighting............5-57
Halogen Bulbs..............................................5-57
Headlamps..................................................5-58
Front Turn Signal, Sidemarker and Daytime
Running Lamps.........................................5-62
Center High-Mounted Stoplamp (CHMSL).........5-63
Taillamps.....................................................5-63
Replacement Bulbs.......................................5-64
Windshield Wiper Blade Replacement..............5-65
Section 5 Service and Appearance Care
5-1
Page 337 of 486

As in the chart shown previously, SAE 5W-30 is the
only viscosity grade recommended for your vehicle. You
should look for and use only oils which have the API
Starburst symbol and which are also identi®ed as
SAE 5W-30. If you cannot ®nd such SAE 5W-30 oils,
you can use an SAE 10W-30 oil which has the API
Starburst symbol, if it's going to be 0ÉF (-18ÉC)
or above. Do not use other viscosity grade oils, such as
SAE 10W-40 or SAE 20W-50 under any conditions.
Notice:Use only engine oil with the American
Petroleum Institute Certi®ed For Gasoline Engines
starburst symbol. Failure to use the recommended
oil can result in engine damage not covered by
your warranty.
GM Goodwrench
žoil meets all the requirements for
your vehicle.
If you are in an area of extreme cold, where the
temperature falls below-20ÉF (-29ÉC), it is
recommended that you use either an SAE 5W-30
synthetic oil or an SAE 0W-30 oil. Both will provide
easier cold starting and better protection for your engine
at extremely low temperatures.
Engine Oil Additives
Don't add anything to your oil. The recommended oils
with the starburst symbol are all you will need for
good performance and engine protection.
When to Change Engine Oil (GM Oil
Life System)
Your vehicle has a computer system that lets you know
when to change the engine oil and ®lter. This is
based on engine revolutions and engine temperature,
and not on mileage. Based on driving conditions,
the mileage at which an oil change will be indicated can
vary considerably. For the oil life system to work
properly, you must reset the system every time the oil is
changed.
When the system has calculated that oil life has been
diminished, it will indicate that an oil change is
necessary. A CHANGE ENGINE OIL message will
come on. Change your oil as soon as possible within
the next two times you stop for fuel. It is possible that, if
you are driving under the best conditions, the oil life
system may not indicate that an oil change is necessary
for over a year.
5-17
Page 373 of 486

Headlamp Aiming
Your vehicle has a visual optical headlamp aiming
system equipped with horizontal aim indicators. The aim
has been preset at the factory and should need no
further adjustment. This is true even though your
horizontal aim indicators may not fall exactly on the
ª0º (zero) marks on their scales.
If your vehicle is damaged in an accident, the headlamp
aim may be affected. Aim adjustment to the low beam
may be necessary if it is difficult to see lane markers (for
horizontal aim), or if oncoming drivers ¯ash their high
beams at you (for vertical aim).
If you believe your headlamps need to be re-aimed, we
recommend that you take your vehicle to your dealer
for service. However, it is possible for you to re-aim your
headlamps as described in the following procedure.
Notice:To make sure your headlamps are aimed
properly, read all the instructions before beginning.
Failure to follow these instructions could cause
damage to headlamp parts.
The vehicle should be properly prepared as follows:
·The vehicle should be placed so the headlamps are
25 ft. (7.6 m) from a light colored wall or other ¯at
surface.
·The vehicle must have all four tires on a perfectly
level surface which is level all the way to the wall
or other ¯at surface.
·The vehicle should be placed so it is perpendicular
to the wall or other ¯at surface.
·The vehicle should not have any snow, ice or mud
attached to it.
·The vehicle should be fully assembled and all other
work stopped while headlamp aiming is being done.
·The vehicle should be normally loaded with a
full tank of fuel and one person or 160 lbs. (75 kg)
on the driver's seat.
·Tires should be properly in¯ated.
·Start the vehicle and rock it to level the suspension.
Headlamp aiming is done with the vehicle low beam
lamps. The high beam lamps will be correctly aimed if
the low beam lamps are aimed properly.
5-53
Page 429 of 486

*1Ð Gasoline Engine and Fuel Injection Rail #2.
*2Ð Gasoline Engine and Fuel Injection Rail #1.
*3Ð Gasoline Engine; Oxygen Sensors.
*4Ð Gasoline Engine; Oxygen Sensors.
*5Ð PCM Ignition
Fuses Usage
GLOW PLUG Not Used
CUST FEED Accessory Power
STUD #1 Auxiliary Power
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 OutletÐRear
Cargo Area and Instrument
Panel
STUD 2Accessory Power/Trailer
Wiring Brake Feed
Fuses Usage
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
TBC BATTTruck Body Controller
Battery Feed
5-109