Highbeam On Light
This light comes on
when the high-beam
headlamps are in use.
SeeHeadlamp High/Low-Beam Changer on
page 149for more information.
Daytime Running Lamps (DRL)
Indicator Light
You have this light on
the instrument panel.
It will light whenever the
DRL are on. It is also
a reminder to turn
on your headlamps
when driving at night.
Tow/Haul Mode Light
This message is
displayed when the
tow/haul mode has
been activated.
For more information, see “Tow/Haul Mode” in
Towing a Trailer on page 269.
Check Gages Warning Light
This light will come on briefly when you are
starting the engine.
United StatesCanada
185
If the light comes on and stays on while you
are driving, check your coolant temperature and
engine oil pressure gages to see if they are in the
warning zones.
Fuel Gage
The fuel gage, when the ignition is on, tells you
about how much fuel you have left in your tank.
The gage will first indicate empty before you
are out of fuel, and you should get more fuel as
soon as possible.Listed are four situations you may experience with
your fuel gage:
•At the gas station, the fuel pump shuts off
before the gage reads full.
•It takes a little more or less fuel to fill up than
the fuel gage indicated. For example, the
gage may have indicated the tank was half full,
but it actually took a little more or less than
half the tank’s capacity to fill the tank.
•The gage moves a little when you turn a
corner or speed up.
•The gage doesn’t go back to empty when you
turn off the ignition.
None of these indicate a problem with the
fuel gage.
United StatesCanada
186
Avoid needless heavy braking. Some people drive
in spurts — heavy acceleration followed by heavy
braking — rather than keeping pace with traffic.
This is a mistake. The brakes may not have time to
cool between hard stops. The brakes will wear out
much faster if you do a lot of heavy braking. If you
keep pace with the traffic and allow realistic
following distances, you will eliminate a lot of
unnecessary braking. That means better braking
and longer brake life.
If your vehicle’s engine ever stops while you are
driving, brake normally but do not pump the
brakes. If you do, the pedal may get harder to
push down. If the engine stops, you will still have
some power brake assist. But you will use it
when you brake. Once the power assist is used
up, it may take longer to stop and the brake pedal
will be harder to push.
Adding non-GM accessories can affect your
vehicle’s performance. SeeAccessories and
Modi cations on page 290.Anti-Lock Brake System (ABS)
Your vehicle has the Anti-Lock Brake System
(ABS), an advanced electronic braking system that
will help prevent a braking skid.
When you start the engine and begin to drive
away, ABS will check itself. You might hear
a momentary motor or clicking noise while this test
is going on. This is normal.
If there is a problem
with the ABS, this
warning light will stay
on. SeeAnti-Lock Brake
System Warning Light
on page 176.
233
{CAUTION:
Snow can trap exhaust gases under your
vehicle. This can cause deadly CO
(carbon monoxide) gas to get inside. CO
could overcome you and kill you. You
cannot see it or smell it, so you might not
know it is in your vehicle. Clear away
snow from around the base of your
vehicle, especially any that is blocking the
exhaust pipe and/or the fuel operated
heater exhaust system, if equipped. And
check around again from time to time to
be sure snow does not collect there. If
your vehicle has a diesel engine and a
fuel operated heater, see “Fuel Operated
Heater (FOH)” in the diesel engine
supplement.
Open a window just a little on the side of
the vehicle that is away from the wind.
This will help keep CO out.Run your engine only as long as you must. This
saves fuel. When you run the engine, make it go a
little faster than just idle. That is, push the
accelerator slightly. This uses less fuel for the heat
that you get and it keeps the battery (or batteries)
charged. You will need a well-charged battery (or
batteries) to restart the vehicle, and possibly for
signaling later on with your headlamps. Let the
heater run for a while.
Then, shut the engine off and close the window
almost all the way to preserve the heat. Start
the engine again and repeat this only when you
feel really uncomfortable from the cold. But do it as
little as possible. Preserve the fuel as long as
you can. To help keep warm, you can get out of
the vehicle and do some fairly vigorous exercises
every half hour or so until help comes.
259
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 fluid (don’t overfill), engine
oil, axle lubricant, belt, cooling system and
brake system. Each of these is covered in this
manual, and the Index will help you find 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.
Trailer Wiring Harness
The optional heavy-duty trailer wiring package
includes a seven-wire harness assembly at the rear
of the vehicle and a four-wire harness assembly
under the left hand side of the instrument panel.
The seven-wire harness assembly is taped together
and located in a frame pocket at the driver side rear
left corner of the frame. The seven-wire harness
includes a 30-amp feed wire.Both harnesses come without connectors and
should be wired by a qualified electrical technician.
The technician can use the following color code
chart when connecting the wiring harness to your
trailer and trailer brake controller.
Seven-Wire Harness
•Light Green: Back-up lamps
•Brown: Parking lamps
•Yellow: Left stoplamp and turn signal
•Dark Green: Right stoplamp and turn signal
•Dark Blue: Use for electric trailer brakes
•Red/Black Stripe: Trailer accessory
•White (heavy gage): Ground wire
Four-Wire Harness (Trailer Brake Controller)
•Black: Ground
•Red/White Stripe: Fused Battery
•Dark Blue: Trailer Brake Feed
•Light Blue: Fused Stoplamp/CHMSL
286
Fuel E85 (85% Ethanol)
The 8th digit of the Vehicle Identification
Number (VIN) shows the code letter or number
that identifies your vehicle’s engine. The VIN is
at the top left of the instrument panel. See
Vehicle Identi cation Number (VIN) on page 392.
If your vehicle has the 5.3L V8 engine (VIN Code Z
only), you can use either regular unleaded gasoline
or ethanol fuel containing up to 85% ethanol (E85);
also seeFuel on page 292. In all other engines,
use only the unleaded gasoline described under
Gasoline Octane on page 293.
Only vehicles that have the 5.3L V8 engine
(VIN Code Z) can use 85% ethanol fuel (E85).
We encourage the use of E85 in vehicles that
are designed to use it. The ethanol in E85
is a “renewable” fuel, meaning it is made from
renewable sources such as corn and other crops.
Many service stations will not have an 85% ethanol
fuel (E85) pump available. The U. S. Department
of Energy has an alternative fuels website
(www.eere.energy.gov/afdc/infrastructure/
locator.html) that can help you find E85 fuel.
Those stations that do have E85 should have a
label indicating ethanol content. Do not use the
fuel if the ethanol content is greater than 85%.At a minimum, E85 should meet ASTM
Specification D 5798. By definition, this means
that fuel labeled E85 will have an ethanol content
between 70% and 85%. Filling the fuel tank
with fuel mixtures that do not meet ASTM
specifications can affect driveability and could
cause the check engine light to come on.
To ensure quick starts in the wintertime, the
E85 fuel must be formulated properly for your
climate according to ASTM specification D 5798.
If you have trouble starting on E85, it could
be because the E85 fuel is not properly formulated
for your climate. If this happens, switching to
gasoline or adding gasoline to the fuel tank can
improve starting. For good starting and heater
efficiency below 32°F (0°C), the fuel mix in the fuel
tank should contain no more than 70% ethanol.
It is best not to alternate repeatedly between
gasoline and E85. If you do switch fuels, it
is recommended that you add as much fuel as
possible — do not add less than three gallons
(11 L) when refueling. You should drive the
vehicle immediately after refueling for at least
seven miles (11 km) to allow the vehicle to adapt
to the change in ethanol concentration.
295
If you are in an area of extreme cold, where the
temperature falls below−20°F (−29°C), it is
recommended that you use either an SAE 5W-30
synthetic oil or an SAE 0W-30 oil. Both provide
easier cold starting and better protection for
the engine at extremely low temperatures.
Engine Oil Additives
Do not add anything to the oil. The recommended
oils with the starburst symbol that meet GM
Standard GM6094M are all you need for good
performance and engine protection.
Engine Oil Life System
(Gasoline Engine)
When to Change Engine Oil
Your vehicle has a computer system that lets you
know when to change the engine oil and filter.
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 light will come on.
SeeChange Engine Oil Light on page 183. Change
the oil as soon as possible within the next 600 miles
(1 000 km). It is possible that, if you are driving
under the best conditions, the oil life system might
not indicate that an oil change is necessary for over
a year. However, the engine oil and filter must be
changed at least once a year and at this time the
system must be reset. Your dealer/retailer has
trained service people who will perform this work
using genuine parts and reset the system. It is also
important to check the oil regularly and keep it at
the proper level.
If the system is ever reset accidentally, you must
change the oil at 3,000 miles (5 000 km) since
your last oil change. Remember to reset the oil life
system whenever the oil is changed.
306
How to Add Automatic
Transmission Fluid
Refer to the Maintenance Schedule to determine
what kind of transmission fluid to use. See
Recommended Fluids and Lubricants on page 415.
Using a funnel, add fluid down the transmission
dipstick tube only after checking the transmission
fluid while it is hot. A cold check is used only
as a reference. If the fluid level is low, add only
enough of the proper fluid to bring the level up to
the HOT area for a hot check. It does not take
much fluid, generally less than one pint (0.5 L).
Do not overfill.
Notice:Use of the incorrect automatic
transmission uid may damage your vehicle,
and the damages may not be covered by
your warranty. Always use the automatic
transmission uid listed inRecommended
Fluids and Lubricants on page 415.
•After adding fluid, recheck the fluid level as
described under “How to Check Automatic
Transmission Fluid,” earlier in this section.
•When the correct fluid level is obtained, push
the dipstick back in all the way; then flip the
handle down to lock the dipstick in place.
Engine Coolant
If your vehicle has the DURAMAX®Diesel engine,
see the DURAMAX®Diesel manual for more
information.
The cooling system in your vehicle is filled with
DEX-COOL
®engine coolant. This coolant is
designed to remain in your vehicle for five years
or 150,000 miles (240 000 km), whichever
occurs first, if you add only DEX-COOL
®
extended life coolant.
The following explains your cooling system and
how to add coolant when it is low. If you have
a problem with engine overheating, seeEngine
Overheating on page 315.
A 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant will:
•Give freezing protection down to−34°F (−37°C).
•Give boiling protection up to 265°F (129°C).
•Protect against rust and corrosion.
•Help keep the proper engine temperature.
•Let the warning lights and gages work as
they should.
312