1999 GMC SIERRA towing

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2-10
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 GM Roadside
Assistance Center.
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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2-14 How to Start the Engine
1. Without pushing the accelerator pedal, turn your
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 right away, hold your key in
START. If it doesn't start in 10 seconds, push the
accelerator pedal all the way down for five more
seconds, unless it starts sooner.3. If your engine still won't start (or starts but then
stops), wait 15 seconds and start over.
When the engine starts, let go of the key and the
accelerator pedal.
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.

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Automatic Transmission Operation
There are several different positions for your shift lever.
If your vehicle is equipped with an automatic
transmission, it features an electronic shift position
indicator within the instrument cluster. This display
must be powered any time 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 disconnect the battery cable
from the battery to prevent discharging your battery.
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).
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.

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AUTOMATIC OVERDRIVE (
): 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.
AUTOMATIC OVERDRIVE (
) 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.
THIRD (3): This position is also used for normal
driving, however it offers more power and lower fuel
economy than AUTOMATIC OVERDRIVE (
).
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), the transmission
will drive in second gear. You may use this feature
for reducing torque to 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.

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Pull the lever, located
just above the parking
brake pedal, marked
BRAKE RELEASE.
If the ignition is on when the parking brake is released,
the brake system warning light will go off.
NOTICE:
Driving with the parking brake on can cause
your rear brakes to overheat. You may have to
replace them, and you could also damage other
parts of your vehicle. Always check to be sure
your parking brake is fully released before
you drive.
If you are towing a trailer and are parking on any hill,
see ªTowing a Trailerº in the Index. That section shows
what to do first to keep the trailer from moving.
If you have a 3500 HD model, it is recommended that
the propshaft
-mounted parking brake be burnished as
part of the new vehicle break
-in. The parking brake
will work best after it has been burnished following
these instructions.
Make 10 stops, using the parking brake foot pedal, from
20 mph (32 km/h) about 2 1/2 miles (4 km) apart. In
between stops, drive the vehicle at 20 mph (32 km/h).

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Shifting Into PARK (P)
(Automatic Transmission Only)
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. 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, use the steps that
follow. With four
-wheel drive if your transfer
case is in NEUTRAL (N), your vehicle will be free
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). If you're pulling a trailer, see
ªTowing a Trailerº in the Index.
1. Hold the brake pedal down with your right foot and
set the parking brake.
2. Move the shift lever into PARK (P) position
like this:

Pull the lever toward you.

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If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P) and the
parking brake is firmly set before you leave it. After you
move the shift lever into PARK (P), hold the regular
brake pedal down. Then, see if you can move the shift
lever away from PARK (P) without first pulling it
toward you. If you can, it means that the shift lever
wasn't fully locked into PARK (P).
Torque Lock (Automatic Transmission)
If you are parking on a hill and you don't shift your
transmission into PARK (P) properly, the weight of the
vehicle may put too much force on the parking pawl in
the transmission. You may find it difficult to pull the
shift lever out of PARK (P). This is called ªtorque lock.º
To prevent torque lock, set the parking brake and then
shift into PARK (P) properly before you leave the
driver's seat. To find out how, see ªShifting Into
PARK (P)º in the Index.
When you are ready to drive, move the shift lever out of
PARK (P) before you release the parking brake.
If torque lock does occur, you may need to have another
vehicle push yours a little uphill to take some of the
pressure from the parking pawl in the transmission, so
you can pull the shift lever out of PARK (P).
Shifting Out of PARK (P)
(Automatic Transmission)
CAUTION:
Before shifting out of PARK (P) you must fully
apply your regular brakes. Your vehicle can roll.
If you have left the engine running, the vehicle
can move suddenly. You or others could be
injured. If you're pulling a trailer, see ªTowing a
Trailerº in the Index.
Your vehicle has a Brake-Transmission Shift Interlock
system (BTSI). You have to fully apply your regular
brakes before you can shift from PARK (P) when the
ignition is in RUN. See ªAutomatic Transmissionº in
the Index.
If you cannot shift out of PARK (P), ease pressure on
the shift lever and push the shift lever all the way up
into PARK (P) as you maintain brake application. Then,
move the shift lever to any gear you want.
If you ever hold the brake pedal down but still can't
shift out of PARK (P), try this:
1. Turn the key to OFF.

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2. Apply and hold the brake until the end of Step 4.
3. Shift to NEUTRAL (N).
4. Start the vehicle and shift to the drive gear you want.
5. Have the Brake
-Transmission Shift Interlock system
fixed as soon as you can.
Parking Your Vehicle
(Manual Transmission Only)
Before you get out of your vehicle, put your manual
transmission in REVERSE (R), turn off the engine, and
firmly apply the parking brake.
If you have four
-wheel-drive, be sure your transfer case
is in a drive gear. Your vehicle could roll if it isn't.
If you are parking on a hill, or if you are pulling a
trailer, see ªTowing a Trailerº in the Index.
CAUTION:
Shifting the transfer case to NEUTRAL (N) can
cause your vehicle to roll even if the manual
transmission is in gear. You or someone else could
be seriously injured. Be sure to set the parking
brake before placing the transfer case in
NEUTRAL (N). See ªParking Brakeº in the Index.
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.