1999 GMC SIERRA hood open

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2-15
Engine Coolant Heater (If Equipped)
In very cold weather,
0
F (
-18
C) or colder,
the engine coolant
heater can help. You'll
get easier starting and
better fuel economy
during engine warm
-up.
Usually, the coolant
heater should be
plugged in a minimum
of four hours prior to
starting your vehicle.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord.
The engine coolant heater electrical cord is located
on the driver's side of the engine compartment, near
the power steering reservoir.3. Plug it into a normal, grounded 110
-volt AC outlet.
CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the wrong
kind of extension cord could overheat and cause
a fire. You could be seriously injured. Plug the
cord into a properly grounded three
-prong
11 0
-volt AC outlet. If the cord won't reach, use a
heavy
-duty three-prong extension cord rated for
at least 15 amps.
4. Before starting the engine, be sure to unplug and store
the cord as it was before to keep it away from moving
engine parts. If you don't, it could be damaged.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead of
trying to list everything here, we ask that you contact
your dealer in the area where you'll be parking your
vehicle. The dealer can give you the best advice for that
particular area.

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5-4
2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren't touching
each other. If they are, it could cause a ground
connection you don't want. You wouldn't be able to
start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake firmly on both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL (N). If you have a four
-wheel-drive
vehicle, be sure the transfer case is not in
NEUTRAL (N).
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off all lamps
that aren't needed as well as radios. This will avoid
sparks and help save both batteries. In addition, it
could save your radio!
NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.
4. Open the hoods and locate the batteries. Find the
positive (+) and negative (
-) terminals on each battery.
CAUTION:
If your vehicle has air conditioning, the auxiliary
electric fan under the hood can start up even
when the engine is not running and can injure
you. Keep hands, clothing and tools away from
any underhood electric fan.

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5-9
Engine Overheating
(Gasoline Engine)
You will find a coolant temperature gage on your
vehicle's instrument panel. See ªEngine Coolant
Temperature Gageº in the Index.
If your vehicle has a diesel engine, see ªEngine
Overheatingº in the Diesel Engine Supplement.
If Steam Is Coming From Your Engine
CAUTION:
Steam from an overheated engine can burn you
badly, even if you just open the hood. Stay away
from the engine if you see or hear steam coming
from it. Just turn it off and get everyone away
from the vehicle until it cools down. Wait until
there is no sign of steam or coolant before you
open the hood.
If you keep driving when your engine is
overheated, the liquids in it can catch fire. You or
others could be badly burned. Stop your engine if
it overheats, and get out of the vehicle until the
engine is cool.
NOTICE:
If your engine catches fire because you keep
driving with no coolant, your vehicle can be
badly damaged. The costly repairs would not be
covered by your warranty.

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5-10 If No Steam Is Coming From Your Engine
If you get an engine overheat warning but see or hear no
steam, the problem may not be too serious. Sometimes
the engine can get a little too hot when you:

Climb a long hill on a hot day.

Stop after high
-speed driving.

Idle for long periods in traffic.

Tow a trailer. See ªDriving on Gradesº in the Index.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. If you have an air conditioner and it's on, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
3. If you're in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
-- AUTOMATIC OVERDRIVE (
)
for automatic transmissions.If you no longer have the overheat warning, you can drive.
Just to be safe, drive slower for about 10 minutes. If the
warning doesn't come back on, you can drive normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there's still no sign of steam, push down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you're parked. If you still have the warning, turn off
the engine and get everyone out of the vehicle until
it cools down.
You may decide not to lift the hood but to get service
help right away.

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6-4
If you're using fuel rated at 87 octane or higher and you
hear heavy knocking, your engine needs service. But
don't worry if you hear a little pinging noise when
you're accelerating or driving up a hill. That's normal,
and you don't have to buy a higher octane fuel to get rid
of pinging. It's the heavy, constant knock that means
you have a problem.
If your vehicle is certified to meet California Emission
Standards (indicated on the underhood emission control
label), it is designed to operate on fuels that meet
California specifications. If such fuels are not available
in states adopting California emissions standards, your
vehicle will operate satisfactorily on fuels meeting
federal specifications, but emission control system
performance may be affected. The malfunction indicator
lamp on your instrument panel may turn on and/or your
vehicle may fail a smog
-check test. (See ªMalfunction
Indicator Lampº in the Index.) If this occurs, return to
your authorized GM dealer for diagnosis to determine
the cause of failure. In the event it is determined that the
cause of the condition is the type of fuels used, repairs
may not be covered by your warranty.Some gasolines that are not reformulated for low
emissions may contain an octane
-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask your service station operator whether
or not his fuel contains MMT. General Motors does not
recommend the use of such gasolines. If fuels containing
MMT are used, spark plug life may be reduced and your
emission control system performance may be affected.
The malfunction indicator lamp on your instrument
panel may turn on. If this occurs, return to your
authorized GM dealer for service.
To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent deposits from forming in your engine and fuel
system, allowing your emission control system to
function properly. Therefore, you should not have
to add anything to the fuel. In addition, gasolines
containing oxygenates, such as ethers and ethanol, and
reformulated gasolines may be available in your area to
contribute to clean air. General Motors recommends that
you use these gasolines, particularly if they comply with
the specifications described earlier.

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6-8
Filling a Portable Fuel Container
CAUTION:
Never fill a portable fuel container while it is in
your vehicle. Static electricity discharge from the
container can ignite the gasoline vapor. You can
be badly burned and your vehicle damaged if this
occurs. To help avoid injury to you and others:

Dispense gasoline only into
approved containers.

Do not fill a container while it is inside a
vehicle, in a vehicle's trunk, pickup bed or
on any surface other than the ground.

Bring the fill nozzle in contact with the
inside of the fill opening before operating
the nozzle. Contact should be maintained
until the filling is complete.

Don't smoke while pumping gasoline.
Checking Things Under the Hood
CAUTION:
If your vehicle has air conditioning, the auxiliary
engine fan under the hood can start up and
injure you even when the engine is not running.
Keep hands, clothing and tools away from any
underhood electric fan.
CAUTION:
Things that burn can get on hot engine parts and
start a fire. These include liquids like gasoline or
diesel fuel, oil, coolant, brake fluid, windshield
washer and other fluids, and plastic or rubber.
You or others could be burned. Be careful not
to drop or spill things that will burn onto a
hot engine.

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6-9 Hood Release
To open the hood, first
pull the handle inside
the vehicle.
Then go to the front of the vehicle and pull up on the
secondary hood release, located just to the passenger's
side of the center of the grill.
Lift the hood.
Before closing the hood, be sure all filler caps are on
properly. Pull down the hood and close it firmly.

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9-5
Gages
Engine Coolant Temperature 2-69 . . . . . . . . . . . . . . . . . . . .
Engine Oil Pressure 2-72 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel 2-75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Speedometer 2-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tachometer 2-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltmeter 2-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Garage Door Opener 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GAWR 4-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gear Positions, Automatic Transmission 2-16 . . . . . . . . . . . . .
Gear Positions, Manual Transmission 2-19, 2-20 . . . . . . . . . .
Glove Box 2-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GM Mobility Program for Persons with Disabilities 8-5 . . . . .
GM Vehicle Care/Appearance Materials 6-68 . . . . . . . . . . . . .
Gross Axle Weight Rating 4-43 . . . . . . . . . . . . . . . . . . . . . . . .
Gross Vehicle Weight Rating 4-43 . . . . . . . . . . . . . . . . . . . . . .
Guide en Fran†ais ii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GVWR 4
-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Halogen Bulbs 6-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hazard Warning Flashers 5-2 . . . . . . . . . . . . . . . . . . . . . . . . . .
Head Restraints 1-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Headlamps 2-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bulb Replacement 6-39, 6-40 . . . . . . . . . . . . . . . . . . . . . . .
High/Low Beam Changer 2-36 . . . . . . . . . . . . . . . . . . . . . .
On Reminder 2-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wiring 6-70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hearing Impaired, Customer Assistance 8-4 . . . . . . . . . . . . . .
Heating 3-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High-Beam Headlamps 2-36 . . . . . . . . . . . . . . . . . . . . . . . . . .
Highway Hypnosis 4-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hill and Mountain Roads 4
-34 . . . . . . . . . . . . . . . . . . . . . . . . .
Hitches, Trailer 4-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hood
Checking Things Under 6
-8 . . . . . . . . . . . . . . . . . . . . . . . . .
Release 6-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Horn 2-35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hydraulic Clutch Fluid 6-24, 7-48 . . . . . . . . . . . . . . . . . . . . . .
Hydraulic Clutch System Check 7-42 . . . . . . . . . . . . . . . . . . .
Hydroplaning 4-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Positions 2-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Transmission Lock Check 7-44 . . . . . . . . . . . . . . . . .
Illuminated Entry 2-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inflation, Tire 6-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inside Day/Night Rearview Mirror 2-44 . . . . . . . . . . . . . . . . .
Inspections 7-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake System 7-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drive Axle 7-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Systems 7-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Radiator and Heater Hose 7-46 . . . . . . . . . . . . . . . . . . . . . .
Steering 7-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Suspension 7-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Linkage 7-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Case (Four-Wheel Drive) 7-47 . . . . . . . . . . . . . . .
Instrument Panel 2-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning 6-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cluster 2-62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse Block 6-71 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Intensity Control 2-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interior Lamps 2-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .