1999 GMC SUBURBAN engine

2-15
OFF (C): This position lets you turn off the engine but
still turn the steering wheel. It doesn't lock the steering
wheel like LOCK. Use OFF if you must have your
vehicle in motion while the engine is off (for example,
if your vehicle is being pushed).
RUN (D): This is the position for driving.
START (E): This position starts your engine.
NOTICE:
If your key seems stuck in LOCK and you can't
turn it, be sure you are using the correct key;
if so, is it all the way in? If it is, then turn the
steering wheel left and right while you turn the
key hard. But turn the key only with your hand.
Using a tool to force it could break the key or the
ignition switch. If none of this works, then your
vehicle needs service.
Retained Accessory Power (If Equipped)
Your vehicle may be equipped with a Retained
Accessory Power (RAP) feature which will allow
certain features on your vehicle to continue to work up
to 20 minutes after the ignition key is turned to OFF.
Your radio, power windows and overhead console will
work when the ignition key is in RUN or ACCESSORY.
Once the key is turned from RUN to OFF, these features
will continue to work for up to 20 minutes or until a
door is opened.
Starting Your Engine
Move your shift lever to PARK (P) or NEUTRAL (N).
Your engine won't start in any other position
-- that's a
safety feature. To restart when you're already moving,
use NEUTRAL (N) only.
NOTICE:
Don't try to shift to PARK (P) if your vehicle
is moving. If you do, you could damage the
transmission. Shift to PARK (P) only when
your vehicle is stopped.

2-16
1. Without pushing the accelerator pedal, turn the
ignition key to START. When the engine starts, let
go of the key. The idle speed will go down as your
engine gets warm.
NOTICE:
Holding your key in START for longer than
15 seconds at a time will cause your battery to
be drained much sooner. And the excessive heat
can damage your starter motor. Wait about
15 seconds between each try to help avoid
draining your battery or damaging your starter.
2. If it doesn't start within 10 seconds, push the
accelerator pedal all the way to the floor, while you
hold the ignition key in START. When the engine
starts, let go of the key and let up on the accelerator
pedal. Wait about 15 seconds between each try to help
avoid draining your battery or damaging your starter.When starting your engine in very cold weather (below
0
F or
-18
C), do this:
1. With your foot off the accelerator pedal, turn the
ignition key to START and hold it there. When the
engine starts, let go of the key. Use the accelerator
pedal to maintain engine speed, if you have to, until
your engine has run for a while.
2. If your engine still won't start (or starts but then stops),
it could be flooded with too much gasoline. Try pushing
your accelerator pedal all the way to the floor and
holding it there as you hold the key in START for about
three seconds. When the engine starts, let go of the
key and accelerator. If the vehicle starts briefly but then
stops again, do the same thing, but this time keep the
pedal down for five or six seconds. This clears the extra
gasoline from the engine.

2-17
NOTICE:
Your engine is designed to work with the
electronics in your vehicle. If you add electrical
parts or accessories, you could change the way
the engine operates. Before adding electrical
equipment, check with your dealer. If you don't,
your engine might not perform properly.
If you ever have to have your vehicle towed,
see the part of this manual that tells how to do
it without damaging your vehicle. See ªTowing
Your Vehicleº in the Index.
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 cord is located on the driver's side of the engine
compartment, near the power steering fluid reservoir.
3. Plug it into a normal, grounded 110
-volt AC outlet.

2-18
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.
Automatic Transmission Operation
There are several different positions for your shift lever.
Your vehicle is equipped with an automatic transmission
and features an electronic shift position indicator within
the instrument panel cluster. This display must be
powered anytime the shift lever is capable of being
moved out of PARK (P). This means that if your key is
in OFF, rather than LOCK, there will be a small current
drain on your battery which could discharge your battery
over a period of time. If you have to leave your key in
the ignition in OFF for an extended period, it is
recommended that you remove the IGN 0 fuse from the
instrument panel fuse block. See ªFuses and Circuit
Breakersº in the Index.

2-19
PARK (P): This locks your rear wheels. It's the best
position to use when you start your engine because your
vehicle can't move easily.
CAUTION:
It is 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 have 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).
CAUTION: (Continued)
CAUTION: (Continued)
If you have four-wheel drive, your vehicle
will be free to roll
-- even if your shift lever
is in PARK (P)
-- if your transfer case is in
NEUTRAL (N). So, be sure the transfer case is in
a drive gear, two
-wheel high (2H) or four-wheel
high (4H) or four
-wheel low (4L) -- not in
NEUTRAL (N). See ªShifting Into PARK (P)º in
the Index. If you're pulling a trailer, see ªTowing
a Trailerº in the Index.
REVERSE (R): Use this gear to back up.
NOTICE:
Shifting to REVERSE (R) while your vehicle is
moving forward could damage your transmission.
Shift to REVERSE (R) only after your vehicle
is stopped.

2-20
To rock your vehicle back and forth to get out of snow,
ice or sand without damaging your transmission, see
ªStuck: In Sand, Mud, Ice or Snowº in the Index.
NEUTRAL (N): In this position, your engine doesn't
connect with the wheels. To restart when you're already
moving, use NEUTRAL (N) only. Also, use NEUTRAL (N)
when your two
-wheel drive vehicle is being towed.
CAUTION:
Shifting out of PARK (P) or NEUTRAL (N) while
your engine is ªracingº (running at high speed)
is dangerous. Unless your foot is firmly on the
brake pedal, your vehicle could move very
rapidly. You could lose control and hit people
or objects. Don't shift out of PARK (P) or
NEUTRAL (N) while your engine is racing.
NOTICE:
Damage to your transmission caused by shifting
out of PARK (P) or NEUTRAL (N) with the
engine racing isn't covered by your warranty.
DRIVE (D): This position is for normal driving. If you
need more power for passing, and you're:

Going less than about 35 mph (56 km/h), push your
accelerator pedal about halfway down.

Going about 35 mph (56 km/h) or more, push the
accelerator all the way down.
You'll shift down to the next gear and have more power.
DRIVE (D) can be used when towing a trailer, carrying
a heavy load, driving on steep hills or for off
-road
driving. You may want to shift the transmission to
THIRD (3) or, if necessary, a lower gear selection if
the transmission shifts too often.

2-21
THIRD (3): This position is also used for normal
driving, however it offers more power and lower fuel
economy than DRIVE (D).
SECOND (2): This position gives you more power but
lower fuel economy. You can use SECOND (2) on hills.
It can help control your speed as you go down steep
mountain roads, but then you would also want to use
your brakes off and on.
If you manually select SECOND (2) in a light duty
automatic transmission, the transmission will drive in
second gear. You may use this feature for reducing the
speed of the rear wheels when you are trying to start
your vehicle from a stop on slippery road surfaces.
FIRST (1): This position gives you even more power
(but lower fuel economy) than SECOND (2). You can
use it on very steep hills, or in deep snow or mud. If the
selector lever is put in FIRST (1) while the vehicle is
moving forward, the transmission won't shift into first
gear until the vehicle is going slowly enough.
NOTICE:
If your rear wheels can't rotate, don't try to
drive. This might happen if you were stuck in
very deep sand or mud or were up against a solid
object. You could damage your transmission.
Also, if you stop when going uphill, don't hold
your vehicle there with only the accelerator
pedal. This could overheat and damage the
transmission. Use your brakes or shift into
PARK (P) to hold your vehicle in position
on a hill.
On cold days, approximately 32
F (0
C) or colder,
your transmission is designed to shift differently until
the engine reaches normal operating temperature.
This is intended to improve heater performance.

2-22 Tow/Haul Mode Selector Switch
Your vehicle is equipped with a tow/haul mode. The
selector switch is located on the end of the column shift
lever. You can use this feature to assist when towing or
hauling a heavy load. See ªTow/Haul Modeº in the
Index for more information.
The Tow/Haul Mode also interacts with the Autoride

feature, if your vehicle is so equipped, to enhance the ride
when trailering or with a loaded vehicle. See ªAutoride
º
in the Index.
Four-Wheel Drive (If Equipped)
If your vehicle has four-wheel drive, you can send your
engine's driving power to all four wheels for extra
traction. To get the most satisfaction out of four
-wheel
drive, you must be familiar with its operation. Read the
part that follows before using four
-wheel drive. See the
appropriate text for the transfer case in your vehicle.
NOTICE:
Driving in the 4-WHEEL HIGH (4H) or
4
-WHEEL LOW (4L) positions for a long time
on dry or wet pavement could shorten the life
of your vehicle's drivetrain.
Front Axle Locking Feature
The front axle locks and unlocks automatically when
you shift the transfer case. Some delay for the axle to
lock or unlock is normal.