light GMC SIERRA 1999 User Guide

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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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Up Shift Light
If you have a manual
transmission, you may have
a SHIFT light. This light
will show you when to shift
to the next higher gear for
best fuel economy.
When this light comes on, you can shift to the next
higher gear if weather, road and traffic conditions let
you. For the best fuel economy, accelerate slowly and
shift when the light comes on.
While you accelerate, it is normal for the light to go on
and off if you quickly change the position of the
accelerator. Ignore the SHIFT light when you downshift.
If your vehicle has four
-wheel drive and is equipped
with a manual transmission, disregard the SHIFT light
when the transfer case is in 4
-Wheel Low.
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. You
should use 2
-WHEEL HIGH (2H) for most normal
driving conditions.
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.

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2-22 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.
Manual Transfer Case (If Equipped)
The transfer case shift lever is on the floor to the right of
the driver. Use this lever to shift into and out of
four
-wheel drive.
The front axle portion of the indicator diagram will light
up when you shift into four
-wheel drive and the front
axle engages.
Some delay between shifting and the indicator's lighting
is normal. If the front axle light does not go out
immediately after you shift out of four
-wheel drive,
have your dealer check your system.
An indicator near the lever shows you the transfer
case settings:
2
-Wheel High (2H): This setting is for driving in most
street and highway situations. Your front axle is not
engaged in two
-wheel drive.

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4-Wheel High (4H): This setting engages your front
axle to help drive your vehicle. Use 4H when you need
extra traction and in most off
-road situations.
CAUTION:
Shifting the transfer case to NEUTRAL (N) can
cause your vehicle to roll even if the transmission
is in PARK (P), or if you have a manual
transmission, even if you are 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.
NEUTRAL (N): Shift to this setting only when your
vehicle needs to be towed or when using a power
take
-off.
4
-Wheel Low (4L): This setting also engages your
front axle to give you extra power and also gives you a
higher driveline ratio. It should be used only for
off
-road driving.
You can shift from 2
-WHEEL HIGH (2H) to
4
-WHEEL HIGH (4H) or from 4-WHEEL HIGH (4H)
to 2
-WHEEL HIGH (2H) while the vehicle is moving.Your front axle will engage faster if you take your foot
off the accelerator for a few seconds after you shift. In
extremely cold weather, it may be necessary to stop or
slow the vehicle to shift into 4
-WHEEL HIGH (4H).
To shift into or out of 4
-WHEEL LOW (4L) or
NEUTRAL (N):
1. Slow the vehicle to a roll, about 1 to 3 mph
(2 to 5 km/h) and shift an automatic transmission
into NEUTRAL (N), or with a manual transmission,
press the clutch pedal.
2. Shift the transfer case shift lever in one
continuous motion.
Don't pause in NEUTRAL (N) as you shift the transfer
case into 4
-WHEEL LOW (4L), or your gears
could clash.
Remember that driving in 4
-WHEEL HIGH (4H) or
4
-WHEEL LOW (4L) may reduce fuel economy. Also,
driving in four
-wheel drive on dry pavement could
cause your tires to wear faster and make your transfer
case harder to shift and run noisier.
When your headlamps or parking lamps are on, rotate the
thumb wheel next to the headlamp switch up to brighten
or down to dim your transfer case indicator light.

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2-24 Electronic Transfer Case (If Equipped)
If your four-wheel-drive vehicle has the electronic
transfer case, the transfer case switches are below and to
the left of the climate control system.Use these switches to shift into and out of four
-wheel
drive. You can choose among three driving settings:
2HI: This setting is for driving in most street and
highway situations. Your front axle is not engaged in
two
-wheel drive.
4HI: This setting engages your front axle to help drive
your vehicle. Use 4HI when you need extra traction, such
as on snowy or icy roads, or in most off
-road situations.
4LO: This setting also engages your front axle to give
you extra traction. You may never need 4LO. It sends
the maximum power to all four wheels. You might
choose 4LO if you were driving off
-road in sand, mud
or deep snow and climbing or descending steep hills.
Indicator lights in the switches show you which setting
you are in. The indicator lights will come on briefly when
you turn on the ignition and the last chosen setting will
stay on. If the lights do not come on, you should take
your vehicle in for service. An indicator light will flash
while shifting. It will remain illuminated when the shift is
completed. If for some reason the transfer cannot make a
requested shift, it will return to the last chosen setting.

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Shifting from 2HI to 4HI
Press and release the 4HI switch. This can be done at
any speed, and the front axle will lock automatically
with some delay.
Shifting from 4HI to 2HI
Press and release the 2HI switch. This can be done at
any speed, and the front axle will unlock automatically
with some delay.
Shifting from 2HI or 4HI to 4LO
To shift from 2HI or 4HI to 4LO, the vehicle must be
stopped or moving less than 3 mph (4.8 km/h) with the
transmission in NEUTRAL (N). The preferred method
for shifting into 4LO is to have your vehicle moving 1 to
2 mph (1.6 to 3.2 km/h). Press and release the 4LO
switch. You must wait for the 4LO indicator light to stop
flashing and remain illuminated before shifting your
transmission into gear.
If the 4LO switch is pressed when your vehicle is in
gear and/or moving, the 4LO indicator light will flash
for 30 seconds and not complete the shift unless your
vehicle is moving slower than 3 mph (4.8 km/h) and the
transmission is in NEUTRAL (N). After 30 seconds the
transfer case will return to 4HI.Shifting from 4LO to 4HI or 2HI
To shift from 4LO to 4HI or 2HI, your vehicle must be
stopped or moving less than 3 mph (4.8 km/h) with the
transmission in NEUTRAL (N). The preferred method
for shifting out of 4LO is to have your vehicle moving
1 to 2 mph (1.6 to 3.2 km/h). Press and release the
4HI switch. You must wait for the 4HI indicator light to
stop flashing and remain illuminated before shifting
your transmission into gear.
If the 4HI switch is pressed when your vehicle is in gear
and/or moving, the 4HI indicator light will flash for 30
seconds but will not complete the shift unless the
vehicle is moving slower than 3 mph (4.8 km/h) and the
transmission is in NEUTRAL (N).
Parking Brake
To set the parking brake, hold the regular brake pedal
down with your right foot. Push down the parking brake
pedal with your left foot.
If the ignition is on, the brake system warning light will
come on.
To release the parking brake, hold the regular brake
pedal down.

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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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2-34
The driver's window also has an express-down feature
that allows the window to be lowered without holding
the switch. Press and hold the side of the window switch
marked AUTO for one second to activate the
express
-down mode. The express-down mode can be
canceled at any time by pressing the opposite side of the
switch. To open the window partway, lightly tap the
switch until the window is at the desired position.
Lockout Switch (Crew Cab)
If you have a Crew Cab and power windows, the power
window switch has a lockout feature. This feature
prevents the rear windows from operating when the
front driver's side switch is in LOCK. The windows can
still be operated using the driver's window switch.
When the switch is moved to NORM, the rear power
windows will operate again.
Swing-Out Windows (Extended Cab)
To open a rear swing-out
window, just flip the
latch open and swing
the glass out.
The latch will catch when the window is fully open and
will hold the window in the open position.
Sliding Rear Window (If Equipped)
To open the sliding rear window, unlock the latch lever
by moving the lever toward the front of the cab. Release
the lever from the latch plate and slide the window
toward the driver's side of the vehicle.
To close the window, slide the window toward the
passenger's side of the vehicle. The latch lever will
automatically snap locked on to the latch plate. Try to
open the window without releasing the latch lever to be
sure the window is in the locked position.

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2-36 Turn Signal and Lane Change Signals
The turn signal has two upward (for right) and two
downward (for left) positions. These positions allow
you to signal a turn or a lane change.
To signal a turn, move the lever all the way up
or down. When the turn is finished, the lever will
return automatically.
An arrow on the instrument
panel will flash in the
direction of the turn or
lane change.
To signal a lane change, just raise or lower the lever
until the arrow starts to flash. Hold it there until you
complete your lane change. The lever will return by
itself when you release it.If you move the lever all the way up or down, and the
arrow flashes at twice the normal rate, a signal bulb
may be burned out and other drivers may not see your
turn signal.
If a bulb is burned out, replace it to help avoid an
accident. If the arrows don't go on at all when you
signal a turn, check for burned
-out bulbs and a blown
fuse (see ªFuses and Circuit Breakersº in the Index).
Headlamp High/Low-Beam Changer
To change the headlamps from low to high beam or high
to low beam, pull the multifunction lever all the way
toward you. Then release it.
When the high beams
are on, this light on the
instrument panel also
will be on.

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2-37 Windshield Wipers
You control the windshield
wipers by turning the knob
with the wiper symbol on it.
For a single wiping cycle, turn the knob to MIST. Hold
it there until the wipers start, then let go. The wipers will
stop after one cycle. If you want more cycles, hold the
knob on MIST longer.
You can set the wiper speed for a long or short delay
between wipes. This can be very useful in light rain or
snow. Turn the knob to choose the delay time. The
closer to LOW, the shorter the delay.For steady wiping at low speed, turn the knob to the
LOW position. For high
-speed wiping, turn the knob
further, to HIGH. To stop the wipers, turn the knob
to OFF.
Damaged wiper blades may prevent you from seeing
well enough to drive safely. To avoid damage, be sure to
clear ice and snow from the wiper blades before using
them. If they are frozen to the windshield, carefully
loosen or thaw them. If your blades do become
damaged, get new blades or blade inserts.
Heavy ice or snow can overload your wipers. The
windshield wiper motor is protected from overload by a
circuit breaker and a fuse. If the motor overheats due to
heavy snow, etc., the wiper will stop until the motor
cools. Although protected from electrical overload,
overload due to heavy snow, etc. may cause wiper
linkage damage. Always clear ice and heavy snow from
the windshield before using your windshield wipers.