1999 GMC YUKON engine

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2-36
Parking Over Things That Burn
CAUTION:
Things that can burn could touch hot exhaust parts
under your vehicle and ignite. Don't park over
papers, leaves, dry grass or other things that can burn.
Engine Exhaust
CAUTION:
Engine exhaust can kill. It contains the gas
carbon monoxide (CO), which you can't see or
smell. It can cause unconsciousness and death.
You might have exhaust coming in if:

Your exhaust system sounds strange
or different.

Your vehicle gets rusty underneath.

Your vehicle was damaged in a collision.

Your vehicle was damaged when driving over
high points on the road or over road debris.

Repairs weren't done correctly.

Your vehicle or exhaust system had been
modified improperly.
If you ever suspect exhaust is coming into
your vehicle:

Drive it only with all the windows down to
blow out any CO; and

Have your vehicle fixed immediately.

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2-37
Running Your Engine While
You're Parked
It's better not to park with the engine running. But if
ever you have to, here are some things to know.
CAUTION:
Idling the engine with the air system control off
could allow dangerous exhaust into your vehicle
(see the earlier Caution under ªEngine Exhaustº).
Also, idling in a closed-in place can let deadly
carbon monoxide (CO) into your vehicle even if
the fan switch is at the highest setting. One place
this can happen is a garage. Exhaust
-- with
CO
-- can come in easily. NEVER park in a
garage with the engine running.
Another closed-in place can be a blizzard.
(See ªBlizzardº in the Index.)
CAUTION:
It can be dangerous to get out of your vehicle if
the shift lever is not fully in PARK (P) with the
parking brake firmly set. Your vehicle can roll.
Don't leave your vehicle when the engine is
running unless you have to. If you've left the
engine running, the vehicle can move suddenly.
You or others could be injured. To be sure your
vehicle won't move, even when you're on fairly
level ground, always set your parking brake and
move the shift lever to PARK (P).
Four-wheel drive vehicles with the transfer case in
NEUTRAL (N) will allow the vehicle to roll, even if
your shift lever is in PARK (P). So, be sure the transfer
case is in a drive gear
-- not in NEUTRAL (N). Always
set your parking brake. Follow the proper steps to be
sure your vehicle won't move. See ªShifting Into
PARK (P)º in the Index.
If you're pulling a trailer, see ªTowing a Trailerº in
the Index.

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2-64
The transmitter will learn and transmit the frequencies
of most current transmitters and is powered by your
vehicle's battery and charging system.
This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions:
(1) this device may not cause harmful interference,
and (2) this device must accept any interference
received, including interference that may cause
undesired operation.
This device complies with RSS
-210 of Industry Canada.
Operation is subject to the following two conditions:
(1) this device may not cause interference, and
(2) this device must accept any interference, including
interference that may cause undesired operation of
the device.
Changes and modifications to this system by other than
an authorized service facility could void authorization to
use this equipment.
Programming the Transmitter
Do not use the transmitter with any garage door opener
that does not have the ªstop and reverseº feature. This
includes any garage door opener model manufactured
before April 1, 1982.
Be sure that people and objects are clear of the garage
door you are programming.
Your vehicle's engine should be turned off while
programming the transmitter. Follow these steps to
program up to three channels.
1. If you have not previously programmed a universal
channel, proceed to Step 2. Otherwise, hold down
the two outside buttons on the universal transmitter
until the red light begins to flash rapidly
(approximately 20 seconds). Then release the
buttons. This procedure initializes the memory and
erases any previous settings for all three channels.
2. Hold the end of the hand
-held transmitter against the
bottom surface of the universal transmitter so that
you can still see the red light.

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2-71 Speedometer and Odometer
Your speedometer lets you see your speed in both miles
per hour (mph) and kilometers per hour (km/h). Your
odometer shows how far your vehicle has been driven,
in either miles (used in the United States) or kilometers
(used in Canada).
Tamper
-Resistant Odometer
Your odometer is tamper
-resistant. The odometer will
show silver lines between the numbers if someone tries
to turn it back.
You may wonder what happens if your vehicle needs a
new odometer installed. Laws vary as to the procedure
that must be followed, so check with your state or
provincial vehicle registration office. But generally, if
the new odometer can be set to the mileage total of the
old odometer, then it must be. But if it can't, then it's set
at zero, and a label must be put on the driver's door to
show the old mileage reading when the new odometer
was installed.Trip Odometer
The trip odometer can tell you how far your vehicle has
been driven since you last set the trip odometer to zero.
To reset the trip odometer, fully press the reset button
located near the trip odometer readout. If the reset
button is not fully pressed, the trip odometer may not go
all the way back to zero. If it doesn't, you may have to
press the reset button again to reset the readout to zero.Tachometer
Your tachometer displays the engine speed in
revolutions per minute (rpm).
NOTICE:
If you operate the engine with the tachometer in
the red area, your engine or other parts could
be damaged.
Damage to your engine or vehicle caused by
operating the engine in the red area isn't covered
by your vehicle warranty. Don't operate the
engine with the tachometer in the red area.

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2-72
Warning Lights, Gages
and Indicators
This part describes the warning lights and gages that
may be on your vehicle. The pictures will help you
locate them.
Warning lights and gages can signal that something is
wrong before it becomes serious enough to cause an
expensive repair or replacement. Paying attention to
your warning lights and gages could also save you or
others from injury.
Warning lights come on when there may be or is a
problem with one of your vehicle's functions. As you
will see in the details on the next few pages, some
warning lights come on briefly when you start the
engine just to let you know they're working. If you are
familiar with this section, you should not be alarmed
when this happens.
Gages can indicate when there may be or is a problem
with one of your vehicle's functions. Often gages and
warning lights work together to let you know when
there's a problem with your vehicle.When one of the warning lights comes on and stays on
when you are driving, or when one of the gages shows
there may be a problem, check the section that tells you
what to do about it. Please follow this manual's advice.
Waiting to do repairs can be costly
-- and even
dangerous. So please get to know your warning lights
and gages. They're a big help.
Safety Belt Reminder Light
When the key is turned to RUN or START, a chime will
come on for about eight seconds to remind people to
fasten their safety belts, unless the driver's safety belt is
already buckled.
The safety belt light will also
come on and stay on for
about 20 seconds, then it will
flash for about 55 seconds. If
the driver's belt is already
buckled, neither the chime
nor the light will come on.

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2-73 Air Bag Readiness Light
There is an air bag readiness light on the instrument
panel, which shows AIR BAG. The system checks the
air bag's electrical system for malfunctions. The light
tells you if there is an electrical problem. The system
check includes the air bag sensors, the air bag modules,
the wiring and the crash sensing and diagnostic module.
For more information on the air bag system, see ªAir
Bagº in the Index.
This light will come on
when you start your engine,
and it will flash for a few
seconds. Then the light
should go out. This means
the system is ready.
If the air bag readiness light stays on after you start the
engine or comes on when you are driving, your air bag
system may not work properly. Have your vehicle
serviced right away.
The air bag readiness light should flash for a few
seconds when you turn the ignition key to RUN. If the
light doesn't come on then, have it fixed so it will be
ready to warn you if there is a problem.
Charging System Warning Light
The charging system
warning light should come
on briefly when you turn on
the ignition, before starting
the engine, as a check to
show you it is working.
After the engine starts, the light should go out. If it stays
on or comes on while you are driving, you may have a
problem with your charging system. It could indicate a
problem with the generator drive belt, or some other
charging system problem. Have it checked right away.
Driving while this light is on could drain your battery.
If you must drive a short distance with this light on, it
helps to turn off all your accessories, such as the radio
and the air conditioner.

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2-74 Voltmeter
When your engine is not
running, but the ignition is
in the RUN position, this
gage shows your battery's
state of charge in DC volts.
When the engine is running, the gage shows the
condition of the charging system. Readings between the
low and high warning zones indicate the normal
operating range.
Readings in the low warning zone may occur when a
large number of electrical accessories are operating in
the vehicle and the engine is left at an idle for an
extended period. This condition is normal since the
charging system is not able to provide full power at
engine idle. As engine speeds are increased, this condition should correct itself as higher engine speeds
allow the charging system to create maximum power.
You can only drive for a short time with the reading in
either warning zone. If you must drive, turn off all
unnecessary accessories.
Readings in either warning zone indicate a possible
problem in the electrical system. Have the vehicle
serviced as soon as possible.
Brake System Warning Light
When the ignition is on, the brake system warning light
will come on when you set your parking brake. The light
will stay on if your parking brake doesn't release fully.
If it stays on after your parking brake is fully released, it
means you have a brake problem.
Your vehicle's hydraulic brake system is divided into
two parts. If one part isn't working, the other part can
still work and stop you. For good braking, though, you
need both parts working well.
If the warning light comes on, there could be a brake
problem. Have your brake system inspected right away.

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2-75
This light should come on
briefly when you turn the
ignition key to RUN. If it
doesn't come on then, have it
fixed so it will be ready to
warn you if there's a problem.
If the light comes on while you are driving, pull off the
road and stop carefully. You may notice that the pedal is
harder to push. Or, the pedal may go closer to the floor.
It may take longer to stop. If the light is still on, have the
vehicle towed for service. (See ªTowing Your Vehicleº
in the Index.)
CAUTION:
Your brake system may not be working properly
if the brake system warning light is on. Driving
with the brake system warning light on can lead
to an accident. If the light is still on after you've
pulled off the road and stopped carefully, have
the vehicle towed for service.
Anti-Lock Brake System Warning Light
With the anti-lock brake
system, this light will come
on when you start your
engine and may stay on
for several seconds.
That's normal.
If the light stays on, or comes on when you're driving,
your vehicle needs service. If the regular brake system
warning light isn't on, you still have brakes, but you
don't have anti
-lock brakes. If the regular brake system
warning light is also on, you don't have anti
-lock brakes
and there's a problem with your regular brakes. See
ªBrake System Warning Lightº earlier in this section.
The anti
-lock brake system warning light should come
on briefly when you turn the ignition key to RUN. If the
light doesn't come on then, have it fixed so it will be
ready to warn you if there is a problem.