Service engine soon GMC YUKON 1999 Owner's Manual

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2-20
Passlock
Your vehicle is equipped with the Passlock
theft
-deterrent system.
Passlock is a passive theft
-deterrent system. Passlock
enables fuel if the ignition lock cylinder is turned with a
valid key. If a correct key is not used or the ignition lock
cylinder is tampered with, fuel is disabled.
During normal operation, the SECURITY light will go
off approximately five seconds after the key is turned to
the RUN ignition position.
If the engine stalls and the SECURITY light flashes,
wait until the light stops flashing before trying to restart
the engine. Remember to release the key from START
as soon as the engine starts.
If the engine is running and the SECURITY light comes
on, you will be able to restart the engine if you turn the
engine off. However, your Passlock system is not working
properly and must be serviced by your dealer. Your vehicle
is not protected by Passlock at this time. You may also
want to check the fuse (see ªFuses and Circuit Breakersº
in the Index). See your dealer for service.
In an emergency, call the GMC Roadside Assistance
Center at 1
-800-GMC-8782 (1-800-462-8782) in the
United States, or 1
-800-268-6800 in Canada.
New Vehicle ªBreak-Inº
NOTICE:
Your vehicle doesn't need an elaborate
ªbreak
-in.º But it will perform better in the long
run if you follow these guidelines:

Keep your speed at 55 mph (88 km/h) or
less for the first 500 miles (805 km).

Don't drive at any one speed
-- fast or
slow
-- for the first 500 miles (805 km).
Don't make full
-throttle starts.

Avoid making hard stops for the first
200 miles (322 km) or so. During this time
your new brake linings aren't yet broken
in. Hard stops with new linings can mean
premature wear and earlier replacement.
Follow this breaking
-in guideline every
time you get new brake linings.

Don't tow a trailer during break
-in. See
ªTowing a Trailerº in the Index for
more information.

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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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2-76 Engine Coolant Temperature Gage
This gage shows the engine
coolant temperature.
It also provides an indicator of how hard your vehicle is
working. During a majority of the operation, the gage
will read 210
F (100
C) or less. If you are pulling a
load or going up hills, it is normal for the temperature to
fluctuate and approach the 260
F (160
C) mark. If the
gage reaches the 260
F (160
C) mark, it indicates that
the cooling system is working beyond its capacity.
The ªProblems on the Road,º section of this manual
shows what to do. See ªEngine Overheatingº in
the Index.
Malfunction Indicator Lamp
(Service Engine Soon Light)
Your vehicle is equipped
with a computer which
monitors operation of the
fuel, ignition and emission
control systems.
This system is called OBD II (On
-Board
Diagnostics
-Second Generation) and is intended to
assure that emissions are at acceptable levels for the life
of the vehicle, helping to produce a cleaner
environment. The SERVICE ENGINE SOON light
comes on to indicate that there is a problem and service
is required. Malfunctions often will be indicated by the
system before any problem is apparent. This may
prevent more serious damage to your vehicle. This
system is also designed to assist your service technician
in correctly diagnosing any malfunction.

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2-77
NOTICE:
If you keep driving your vehicle with this light
on, after a while, your emission controls may not
work as well, your fuel economy may not be as
good and your engine may not run as smoothly.
This could lead to costly repairs that may not be
covered by your warranty.
NOTICE:
Modifications made to the engine, transmission,
exhaust or fuel system of your vehicle or the
replacement of the original tires with other than
those of the same Tire Performance Criteria
(TPC) can affect your vehicle's emission controls
and may cause the SERVICE ENGINE SOON
light to come on. Modifications to these systems
could lead to costly repairs not covered by your
warranty. This may also result in a failure to pass
a required Emission Inspection/Maintenance test.
This light should come on, as a check to show you it is
working, when the ignition is on and the engine is not
running. If the light doesn't come on, have it repaired.
This light will also come on during a malfunction in one
of two ways:

Light Flashing
-- A misfire condition has been
detected. A misfire increases vehicle emissions and
may damage the emission control system on your
vehicle. Dealer or qualified service center diagnosis
and service may be required.

Light On Steady
-- An emission control system
malfunction has been detected on your vehicle.
Dealer or qualified service center diagnosis and
service may be required.
If the Light Is Flashing
The following may prevent more serious damage to
your vehicle:

Reducing vehicle speed.

Avoiding hard accelerations.

Avoiding steep uphill grades.

If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.

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2-79 Oil Pressure Gage
The oil pressure gage shows
the engine oil pressure in psi
(pounds per square inch)
when the engine is running.
Canadian vehicles indicate
pressure in kPa (kilopascals).
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.
A reading in the low pressure zone may be caused by a
dangerously low oil level or other problem causing low
oil pressure. Check your oil as soon as possible.CAUTION:
Don't keep driving if the oil pressure is low. If
you do, your engine can become so hot that it
catches fire. You or others could be burned.
Check your oil as soon as possible and have your
vehicle serviced.
NOTICE:
Damage to your engine from neglected oil
problems can be costly and is not covered by
your warranty.

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5-12
CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Don't touch them. If you
do, you can be burned.
Don't run the engine if there is a leak. If you run
the engine, it could lose all coolant. That could
cause an engine fire, and you could be burned.
Get any leak fixed before you drive the vehicle.
NOTICE:
Engine damage from running your engine
without coolant isn't covered by your warranty.
NOTICE:
When adding coolant, it is important that you use
only DEX-COOL
(silicate-free) coolant.
NOTICE: (Continued)
NOTICE: (Continued)
If coolant other than DEX-COOL is added to the
system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the use
of coolant other than DEX-COOL

is not
covered by your new vehicle warranty.
If there seems to be no leak, start the engine again. See
if the engine cooling fan speed increases when idle
speed is doubled by pushing the accelerator pedal down.
If it doesn't, your vehicle needs service. Turn off
the engine.
How to Add Coolant to the Coolant
Recovery Tank
If you haven't found a problem yet, but the coolant level
isn't at or above the COLD mark, add a 50/50 mixture
of clean, drinkable water and DEX
-COOL
engine
coolant at the coolant recovery tank. (See ªEngine
Coolantº in the Index for more information.)

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6-14 When to Change Engine Oil
If any one of these is true for you, use the short trip/city
maintenance schedule:

Most trips are less than 5 to 10 miles (8 to 16 km).
This is particularly important when outside
temperatures are below freezing.

Most trips include extensive idling (such as frequent
driving in stop
-and-go traffic).

You operate your vehicle in dusty areas or
off
-road frequently.

You frequently tow a trailer or use a carrier on top of
your vehicle.

The vehicle is used for delivery service, police, taxi
or other commercial application.
Driving under these conditions causes engine oil to
break down sooner. If any one of these is true for your
vehicle, then you need to change your oil and filter
every 3,000 miles (5 000 km) or 3 months
-- whichever
occurs first.
If none of them is true, use the long trip/highway
maintenance schedule. Change the oil and filter every7,500 miles (12 500 km) or 12 months
-- whichever
occurs first. Driving a vehicle with a fully warmed
engine under highway conditions causes engine oil to
break down slower.
What to Do with Used Oil
Did you know that used engine oil contains certain
elements that may be unhealthy for your skin and could
even cause cancer? Don't let used oil stay on your skin
for very long. Clean your skin and nails with soap and
water, or a good hand cleaner. Wash or properly throw
away clothing or rags containing used engine oil. (See
the manufacturer's warnings about the use and disposal
of oil products.)
Used oil can be a real threat to the environment. If you
change your own oil, be sure to drain all free
-flowing oil
from the filter before disposal. Don't ever dispose of oil
by putting it in the trash, pouring it on the ground, into
sewers, or into streams or bodies of water. Instead,
recycle it by taking it to a place that collects used oil. If
you have a problem properly disposing of your used oil,
ask your dealer, a service station or a local recycling
center for help.

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6-31
NOTICE:

Using the wrong fluid can badly damage
brake system parts. For example, just a few
drops of mineral
-based oil, such as engine
oil, in your brake system can damage brake
system parts so badly that they'll have to be
replaced. Don't let someone put in the
wrong kind of fluid.

If you spill brake fluid on your vehicle's
painted surfaces, the paint finish can be
damaged. Be careful not to spill brake fluid
on your vehicle. If you do, wash it off
immediately. See ªAppearance Careº in
the Index.
Brake Wear
Your vehicle has front disc brakes and rear drum brakes.
Disc brake pads have built
-in wear indicators that make a
high
-pitched warning sound when the brake pads are worn
and new pads are needed. The sound may come and go or
be heard all the time your vehicle is moving (except when
you are pushing on the brake pedal firmly).
CAUTION:
The brake wear warning sound means that soon
your brakes won't work well. That could lead to
an accident. When you hear the brake wear
warning sound, have your vehicle serviced.
NOTICE:
Continuing to drive with worn-out brake pads
could result in costly brake repair.
Some driving conditions or climates may cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
your brakes.

Scheduled Maintenance
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7-5
Short Trip/City Definition
Follow the Short Trip/City Maintenance Schedule if any
one of these conditions is true for your vehicle:

Most trips are less than 5 to 10 miles (8 to 16 km).
This is particularly important when outside
temperatures are below freezing.

Most trips include extensive idling (such as frequent
driving in stop
-and-go traffic).

You operate your vehicle in dusty areas or
off
-road frequently.

You frequently tow a trailer or use a carrier on top of
your vehicle.

If the vehicle is used for delivery service, police, taxi
or other commercial application.
One of the reasons you should follow this schedule if
you operate your vehicle under any of these conditions
is that these conditions cause engine oil to break
down sooner.
Short Trip/City Intervals
Every 3,000 Miles (5 000 km): Engine Oil and Filter
Change (or 3 months, whichever occurs first). Chassis
Lubrication (or 3 months, whichever occurs first). Drive
Axle Service (or 3 months, whichever occurs first).
Every 6,000 Miles (10 000 km): Tire Rotation.
Every 30,000 Miles (50 000 km): Fuel Filter Replacement.
Every 50,000 Miles (83 000 km): Automatic
Transmission Service (severe conditions only).
Every 60,000 Miles (100 000 km): Engine Accessory
Drive Belt Inspection. Fuel Tank, Cap and Lines
Inspection. Exhaust Gas Recirculation System
Inspection. Evaporative Control System Inspection.
Every 100,000 Miles (166 000 km): Spark Plug Wire
Inspection. Spark Plug Replacement. Automatic
Transmission Service (normal conditions). Positive
Crankcase Ventilation (PCV) Valve Inspection.
Every 150,000 Miles (240 000 km): Cooling System
Service (or every 60 months, whichever occurs first).
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.

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9-6
Labels
Certification/Tire 4-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Parts Identification 6-55 . . . . . . . . . . . . . . . . . . . . .
Tire-Loading Information 4-43 . . . . . . . . . . . . . . . . . . . . . .
Vehicle Identification Number 6-55 . . . . . . . . . . . . . . . . . . .
Lamps 2-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Automatic 2-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning Exterior 6-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Delay 2-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dome 2-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exterior 2-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fog 2-48, 6-36, 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interior 2-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Reminder 2-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leaving Your Vehicle 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leaving Your Vehicle with the Engine Running 2-34 . . . . . . .
Lighter 2-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lights
Air Bag Readiness 1
-25, 2-73 . . . . . . . . . . . . . . . . . . . . . . .
Anti-Lock Brake System Warning 2-75, 4-7 . . . . . . . . . . . .
Brake System Warning 2-74 . . . . . . . . . . . . . . . . . . . . . . . . .
Charging Warning System 2-73 . . . . . . . . . . . . . . . . . . . . . .
Check Gages 2-81 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps Indicator 2-81 . . . . . . . . . . . . . . .
Headlamp High-Beam Indicator 2-81 . . . . . . . . . . . . . . . . .
Safety Belt Reminder 1-10, 2-72 . . . . . . . . . . . . . . . . . . . . .
Security 2-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Engine Soon 2-76 . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Four-Wheel Drive 2-80 . . . . . . . . . . . . . . . . . . . . . .
Turn Signal and Lane Change Indicator 2-81 . . . . . . . . . . .
Loading Your Vehicle 4-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . Loading Your Vehicle for Off
-Road Driving 4-15 . . . . . . . . . .
Lockout Prevention 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Locks 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Child Security 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder 7-36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Door 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Transmission Check 7-38 . . . . . . . . . . . . . . . . . . . .
Key Lock Cylinder Service 7-36 . . . . . . . . . . . . . . . . . . . . .
Power Door 2-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Window 2-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants and Fluids 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubrication, Weatherstrips 6-50, 7-36 . . . . . . . . . . . . . . . . . . .
Lubrication Service, Body 7-36 . . . . . . . . . . . . . . . . . . . . . . . .
Luggage Carrier 2-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance, Normal Replacement Parts 6-65 . . . . . . . . . . .
Maintenance Record 7-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance Schedule 7-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Long Trip/Highway Definition 7-6 . . . . . . . . . . . . . . . . . . .
Long Trip/Highway Intervals 7-6 . . . . . . . . . . . . . . . . . . . . .
Owner Checks and Services 7-35 . . . . . . . . . . . . . . . . . . . . .
Periodic Maintenance Inspections 7-39 . . . . . . . . . . . . . . . .
Recommended Fluids and Lubricants 7-41 . . . . . . . . . . . . .
Scheduled Maintenance Services 7-4 . . . . . . . . . . . . . . . . . .
Short Trip/City Definition 7-5 . . . . . . . . . . . . . . . . . . . . . . .
Short Trip/City Intervals 7-5 . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance, Underbody 6-53 . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance When Trailer Towing 4-53 . . . . . . . . . . . . . . . . .
Malfunction Indicator Lamp 2-76 . . . . . . . . . . . . . . . . . . . . . .
Methanol 6-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .