2003 GMC ENVOY hood open

Engine Coolant Heater
Your vehicle may have this feature. In very cold
weather, 0ÉF (-18ÉC) 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. At temperatures
above 32ÉF (0ÉC), use of the coolant heater is not
required.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord. The
cord is located on the driver's side of the engine
compartment, behind the battery.
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 ®re. You could be seriously
injured. Plug the cord into a properly grounded
three-prong 110-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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Checking Things Under
the Hood
{CAUTION:
Things that burn can get on hot engine parts
and start a ®re. These include liquids like fuel,
oil, coolant, brake ¯uid, windshield washer and
other ¯uids, 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.
Hood Release
1. To open the hood, ®rst
pull the handle located
inside the vehicle
on the lower driver's
side of the instrument
panel.
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Engine Compartment Overview
When you open the hood on the L6 engine, you'll see the following:
5-12

When you open the hood on the V8 engine, you'll see the following:
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Engine Overheating
You will ®nd a coolant temperature gage on your
vehicle's instrument panel. If your vehicle has a DIC,
the display will show an Engine Coolant Hot/Idle Engine
message.
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 ®re. 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 ®re 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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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.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in neutral while
stopped. If it is safe to do so, pull off the road,
shift to PARK (P) or NEUTRAL (N) and let
the engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.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 and you have not stopped, pull
over, stop, and park your vehicle right away.
If there's still no sign of steam, you can 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 vehicleuntil it
cools down.
You may decide not to lift the hood but to get service
help right away.
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Notice:Ignoring these steps could result in costly
damage to your vehicle that wouldn't be covered
by your warranty.
Trying to start your vehicle by pushing or pulling it
won't work, and it could damage your vehicle.
1. Check the other vehicle. It must have a 12-volt
battery with a negative ground system.
Notice:If the other system isn't a 12-volt system
with a negative ground, both vehicles can be
damaged.
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 ®rmly on both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL before setting the parking brake. If
you have a four-wheel-drive vehicle, be sure
the transfer case is not in NEUTRAL.
Notice:If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets (if equipped).
Turn off the radio and all lamps that aren't needed.
This will avoid sparks and help to save both
batteries. And it could save your radio!
4. Open both hoods and locate the batteries. Find the
positive (+) and negative (-) terminals on each
battery. Your vehicle has a remote negative (-) jump
starting terminal. You should always use this
remote terminal instead of the terminal on the
battery. The remote negative (-) terminal is located
on the front engine lift bracket on vehicles with
the L6 engine or the engine accessory drive bracket
for vehicles with the V8 engine, and is marked
ªGND.º See
Engine Compartment Overview
on page 5-12for more information on location.
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When the differential is cold, add enough lubricant
to raise the level to 1/2 inch (12 mm) below the ®ller
plug hole.
When the differential is at operating temperature
(warm), add enough lubricant to raise the level to the
bottom of the ®ller plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. SeePart D: Recommended
Fluids and Lubricants on page 6-18.
Bulb Replacement
For the type of bulbs, seeReplacement Bulbs on
page 5-52.
For any bulb changing procedure not listed in this
section, contact your dealer.
Halogen Bulbs
{CAUTION:
Halogen bulbs have pressurized gas inside
and can burst if you drop or scratch the bulb.
You or others could be injured. Be sure to read
and follow the instructions on the bulb
package.
Headlamps
1. Open the hood.
2. Lift the inner quick release clips.
3. Pull the headlamp assembly away from the vehicle.
4. Remove the cover from the headlamp bulb.
5. Disconnect the wiring harness.
6. Remove the headlamp bulb by turning the socket
counterclockwise.
7. To install the replacement bulb, reverse Steps 1
through 6.
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