2004 GMC SIERRA engine overheat

TRANS HOT IDLE ENGINE
(Allison TransmissionžOnly)
If the transmission ¯uid in the vehicle gets hot, this
message will appear on the DIC, and you will hear a
chime. The chime will stop when the transmission ¯uid
temperature is less that 265ÉF (129ÉC). Driving with
the transmission ¯uid temperature high can cause
damage to the vehicle. Stop the vehicle and let it idle to
allow the transmission to cool. This message will
clear when the ¯uid temperature reaches a safe level.
Notice:If you drive your vehicle while the
transmission ¯uid is overheating and the
transmission temperature warning is displayed on
the instrument panel cluster and/or DIC, you
can damage the transmission. This could lead to
costly repairs that would not be covered by
your warranty. Do not drive your vehicle with
overheated transmission ¯uid or while transmission
temperature warning is displayed.
TURN SIGNAL ON
If a turn signal is left on for 3/4 of a mile (1.2 km), this
message will appear on the display and you will
hear a chime. Move the turn signal/multifunction lever to
the off position. Press the select button to acknowledge
the message and clear it from the DIC display.
Audio System(s)
Notice:Before you add any sound equipment to
your vehicle ± like a tape player, CB radio, mobile
telephone or two-way radio ± be sure you can
add what you want. If you can, it's very important to
do it properly. Added sound equipment may
interfere with the operation of your vehicle's engine,
radio or other systems, and even damage them.
Your vehicle's systems may interfere with the
operation of sound equipment that has been added
improperly.
So, before adding sound equipment, check with
your dealer and be sure to check federal rules
covering mobile radio and telephone units.
Your audio system has been designed to operate easily
and to give years of listening pleasure. You will get
the most enjoyment out of it if you acquaint yourself with
it ®rst. Figure out which radio you have in your vehicle,
®nd out what your audio system can do and how to
operate all of its controls to be sure you're getting the
most out of the advanced engineering that went into it.
Your vehicle may have a feature called Retained
Accessory Power (RAP). With RAP, you can play your
audio system even after the ignition is turned off.
See ªRetained Accessory Power (RAP)º under
Ignition
Positions on page 2-22.
3-73

Driving Downhill
When off-roading takes you downhill, you will want to
consider a number of things:
·How steep is the downhill? Will I be able to maintain
vehicle control?
·What is the surface like? Smooth? Rough?
Slippery? Hard-packed dirt? Gravel?
·Are there hidden surface obstacles? Ruts? Logs?
Boulders?
·What is at the bottom of the hill? Is there a hidden
creek bank or even a river bottom with large
rocks?
If you decide you can go down a hill safely, then try to
keep your vehicle headed straight down, and use a
low gear. This way, engine drag can help your brakes
and they will not have to do all the work. Descend
slowly, keeping your vehicle under control at all times.
{CAUTION:
Heavy braking when going down a hill can
cause your brakes to overheat and fade. This
could cause loss of control and a serious
accident. Apply the brakes lightly when
descending a hill and use a low gear to keep
vehicle speed under control.
Q:Are there some things I should not do when
driving down a hill?
A:Yes! These are important because if you ignore
them you could lose control and have a serious
accident.
·When driving downhill, avoid turns that take you
across the incline of the hill. A hill that is not too
steep to drive down may be too steep to drive
across. You could roll over if you do not drive
straight down.
4-31

·Never go downhill with the transmission in
NEUTRAL (N), or with the clutch pedal pressed
down in a manual shift. This is called
ªfree-wheeling.º Your brakes will have to do all the
work and could overheat and fade.
Q:Am I likely to stall when going downhill?
A:It is much more likely to happen going uphill. But if
it happens going downhill, here is what to do.
·Stop your vehicle by applying the regular brakes.
Apply the parking brake.
·Shift to PARK (P) (or to neutral with the manual
transmission) and, while still braking, restart the
engine.
·Shift back to a low gear, release the parking brake,
and drive straight down.
·If the engine will not start, get out and get help.
Driving Across an Incline
Sooner or later, an off-road trail will probably go across
the incline of a hill. If this happens, you have to
decide whether to try to drive across the incline. Here
are some things to consider:
·A hill that can be driven straight up or down may be
too steep to drive across. When you go straight up
or down a hill, the length of the wheel base (the
distance from the front wheels to the rear wheels)
reduces the likelihood the vehicle will tumble
end over end. But when you drive across an incline,
the much more narrow track width (the distance
between the left and right wheels) may not prevent
the vehicle from tilting and rolling over. Also,
driving across an incline puts more weight on the
downhill wheels. This could cause a downhill
slide or a rollover.
·Surface conditions can be a problem when you
drive across a hill. Loose gravel, muddy spots,
or even wet grass can cause your tires to slip
sideways, downhill. If the vehicle slips sideways,
it can hit something that will trip it (a rock, a rut, etc.)
and roll over.
·Hidden obstacles can make the steepness of the
incline even worse. If you drive across a rock with the
uphill wheels, or if the downhill wheels drop into a rut
or depression, your vehicle can tilt even more.
4-32

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.
If You Are Stuck: In Sand, Mud, Ice
or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you do not want to
spin your wheels too fast. The method known as
ªrockingº can help you get out when you are stuck, but
you must use caution.
{CAUTION:
If you let your tires spin at high speed, they
can explode, and you or others could be
injured. And, the transmission or other parts of
the vehicle can overheat. That could cause an
engine compartment ®re or other damage.
When you are stuck, spin the wheels as little
as possible. Do not spin the wheels above
35 mph (55 km/h) as shown on the
speedometer.
Notice:Spinning your wheels can destroy parts of
your vehicle as well as the tires. If you spin the
wheels too fast while shifting your transmission
back and forth, you can destroy your transmission.
For more information about using tire chains on your
vehicle, see
Tire Chains on page 5-94.
4-51

Turn Signals When Towing a Trailer
The arrows on your instrument panel will ¯ash whenever
you signal a turn or lane change. Properly hooked up,
the trailer lamps will also ¯ash, telling other drivers
you're about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel will ¯ash for turns even if the bulbs on the trailer
are burned out. Thus, you may think drivers behind
you are seeing your signal when they are not. It's
important to check occasionally to be sure the trailer
bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gearbeforeyou start
down a long or steep downgrade. If you don't shift
down, you might have to use your brakes so much that
they would get hot and no longer work well.
If you have an automatic transmission, you can tow in
DRIVE (D). You may want to shift the transmission
to lower gear selection if the transmission shifts too often
(e.g., under heavy loads and/or hilly conditions).
You may also want to activate the tow/haul mode if the
transmission shifts too often. See
Tow/Haul Mode
Light on page 3-53.If you have a 5-speed manual transmission and you are
towing a trailer, it's better not to use FIFTH (5) gear.
Just drive in FOURTH (4) gear (or, as you need
to, a lower gear).
If you have a 6-speed manual transmission and you are
towing a trailer, it's better not to use SIXTH (6) gear.
Drive in FIFTH (5) gear (or, as you need to, a lower gear).
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes. If you turn your
engine off immediately after towing at high altitude
on steep uphill grades, your vehicle may show signs
similar to engine overheating. To avoid this, let the
engine run while parked, preferably on level ground, with
the automatic transmission in PARK (P) for a few
minutes before turning the engine off. For manual
transmissions, let the engine run while parked,
preferably on level ground, with the transmission out of
gear and the parking brake applied, for a few minutes
before turning the engine off. If you do get the overheat
warning, see
Engine Overheating on page 5-36.
4-93

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...................................................5-18
Engine Air Cleaner/Filter................................5-23
Automatic Transmission Fluid (Except Allison
Transmission
ž) ..........................................5-25
Automatic Transmission Fluid (Allison
Transmission
ž) ..........................................5-28
Manual Transmission Fluid.............................5-31
Hydraulic Clutch...........................................5-32
Engine Coolant.............................................5-33
Coolant Surge Tank Pressure Cap..................5-36
Engine Overheating.......................................5-36Cooling System............................................5-39
Engine Fan Noise.........................................5-44
Power Steering Fluid.....................................5-45
Windshield Washer Fluid................................5-46
Brakes........................................................5-48
Battery........................................................5-52
Jump Starting...............................................5-53
Rear Axle.......................................................5-59
Four-Wheel Drive............................................5-60
Noise Control System.....................................5-62
Tampering with Noise Control System
Prohibited.................................................5-62
Bulb Replacement..........................................5-64
Halogen Bulbs..............................................5-64
Headlamps..................................................5-64
Front Turn Signal, Sidemarker and Daytime
Running Lamps.........................................5-66
Roof Marker Lamps......................................5-67
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp.............................................5-69
Pickup Box Identi®cation and Fender Marker
Lamps.....................................................5-70
Taillamps.....................................................5-71
Replacement Bulbs.......................................5-74
Section 5 Service and Appearance Care
5-1

Automatic Transmission Fluid
(Except Allison Transmission
ž)
When to Check and Change
A good time to check your automatic transmission ¯uid
level is when the engine oil is changed.
Change both the ¯uid and ®lter every 50,000 miles
(83 000 km) if the vehicle's GVWR is over 8,600 or if
the vehicle is mainly driven under one or more of these
conditions:
·In heavy city traffic where the outside temperature
regularly reaches 90ÉF (32ÉC) or higher.
·In hilly or mountainous terrain.
·When doing frequent trailer towing.
·Uses such as found in taxi, police or delivery
service.
If your vehicle's GVWR is not over 8,600 and you do
not use your vehicle under any of these conditions,
change the ¯uid and ®lter every 100,000 miles
(166 000 km).
See
Scheduled Maintenance on page 6-4.
How to Check
Because this operation can be a little difficult, you may
choose to have this done at the dealership service
department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little ¯uid can damage
your transmission. Too much can mean that some
of the ¯uid could come out and fall on hot engine
part or exhaust system parts, starting a ®re.
Too little ¯uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission ¯uid.
Wait at least 30 minutes before checking the
transmission ¯uid level if you have been driving:
·When outside temperatures are above 90ÉF (32ÉC).
·At high speed for quite a while.
·In heavy traffic ± especially in hot weather.
·While pulling a trailer.
To get the right reading, the ¯uid should be at normal
operating temperature, which is 180ÉF to 200ÉF
(82ÉC to 93ÉC).
5-25

Automatic Transmission Fluid
(Allison Transmission
ž)
When to Check and Change
A good time to check your automatic transmission ¯uid
level is when the engine oil is changed.
Change both the ¯uid and ®lter every 25,000 miles
(41 500 km) if the vehicle is mainly driven under one or
more of these conditions:
·In heavy city traffic where the outside temperature
regularly reaches 90ÉF (32ÉC) or higher.
·In hilly or mountainous terrain.
·When doing frequent trailer towing.
·Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the ¯uid and ®lter every
50,000 miles (83 000 km).
See
Scheduled Maintenance on page 6-4.
How to Check
Because this operation can be a little difficult, you may
choose to have this done at the dealership service
department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little ¯uid can damage
your transmission. Too much can mean that some
of the ¯uid could come out and fall on hot engine
part or exhaust system parts, starting a ®re.
Too little ¯uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission ¯uid.
Wait at least 30 minutes before checking the
transmission ¯uid level if you have been driving:
·When outside temperatures are above 90ÉF (32ÉC).
·At high speed for quite a while.
·In heavy traffic ± especially in hot weather.
·While pulling a trailer.
5-28