2001 GMC SIERRA engine

3-7
With the automatic setting, the air conditioning
compressor automatically cycles when needed to cool the
air. In cold weather, when the system senses the need for
heat, the airflow will be directed out of the floor outlets.
As the interior temperature approaches a desired setting,
the blower speed will decrease. To maintain interior
comfort, the airflow will adjust between the instrument
panel air outlets and floor outlets. On bright sunny days
in cool weather, the airflow may come out of the air
conditioning and floor outlets (bi
-level mode) to
maintain comfort and prevent stuffiness.
To avoid blowing cold air in cold weather, the system
will delay turning on the fan until warm air is available.
The length of delay depends on the outside air
temperature, engine coolant temperature or the time since
the engine was last started. As the coolant warms up, the
fan speed will gradually increase and air will flow from
the heater outlets, with some airflow to the windshield
to prevent fogging under most normal conditions.
Be careful not to put anything over the solar sensor
located around the center of the instrument panel.
This sensor is used by the automatic system to
regulate temperature.Mode Knob
-- Manual Operation
The right knob on the control panel allows you to
choose the direction of air delivery.
You can choose to set the climate control system
yourself, or let the system work for you by placing the
system in AUTO mode. See ªMode Knob
-- Automatic
Operationº earlier in this section.
PANEL: This setting directs most of the air
through the instrument panel outlets and a small amount
through the floor outlets.
BI-LEVEL: Air is delivered through the heater
floor outlets as well as the instrument panel outlets.
HEATER: This setting directs most of the
warmed air through the heater floor outlets and some
air through the windshield defroster outlets.
BLEND: Airflow is divided equally between the
heater floor outlet and the windshield defroster outlets.
The air conditioning compressor may run to dehumidify
the air to prevent window fogging.

3-13 Heating
The heater works best if you keep your windows closed
while using it. On cold days, use the HEATER or
VENT/HEAT setting with the temperature knob in the
red area.
On cold days, approximately 32
F (
-0
C) or lower,
if your vehicle is equipped with an automatic transmission,
you may experience differences in how the transmission
shifts until the engine is warm. This feature automatically
reduces the time it takes for the engine to reach normal
operating temperature and shortens the time it takes the
heater to reach full output.
If you use the engine coolant heater before starting your
engine in cold weather, 20
F (
-8
C) or lower, the
heating system will produce warmer air faster to heat the
passenger compartment.
The use of an engine coolant heater also reduces the
time it takes for the engine to reach normal operating
temperature. For more information, see ªEngine Coolant
Heaterº in the Index.
Defogging and Defrosting
On cool, humid days, use DEFOG to keep the
windshield and side windows clear. Use DEFROST to
remove fog or ice from the windshield in extremely
humid or cold conditions. Use DEFROST with the
temperature knob toward the red area and the fan
control turned all the way to the right.
Rear Window Defogger (If Equipped)
If you see lines running across the rear window, you
have a rear window defogger. The lines warm the glass.
To turn on the rear window
defogger, press this button
next to the fan knob.
The rear window
defogger will only work
if the ignition is in RUN.
For best results, clear the
window of as much snow
or ice as possible.

3-16
Audio Systems
Your audio system has been designed to operate easily
and give years of listening pleasure. You will get the
most enjoyment out of it if you acquaint yourself with it
first. Find out what your audio system can do and how
to operate all its controls, to be sure you're getting the
most out of the advanced engineering that went into it.
Setting the Clock for Systems with
SET Button
Press SET. Within five seconds, press and hold the
SEEK right arrow until the correct minute appears on
the display. Press and hold the SEEK left arrow until
the correct hour appears on the display.
Setting the Clock for Systems with HR
and MN Buttons
Press and hold HR until the correct hour appears on
the display. Press and hold MN until the correct minute
appears on the display. To display the clock with the
ignition off, press RECALL or HR/MN and the time
will be displayed for a few seconds. There is an initial
two
-second delay before the clock goes into the
time
-set mode.
AM-FM Stereo
Playing the Radio
VOLUME: This knob turns the system on and off and
controls the volume. To increase volume and turn the radio
on, turn the knob clockwise. Turn it counterclockwise to
decrease volume and turn the radio off.
RECALL: Display the time with the ignition off by
pressing the recall knob. When the radio is playing,
press this knob to recall the station frequency.
Finding a Station
AM
-FM: Press the lower knob to switch between
AM and FM. The display shows your selection.
TUNE: Turn the lower knob to tune in radio stations.

3-33 Tips About Your Audio System
Hearing damage from loud noise is almost undetectable
until it is too late. Your hearing can adapt to higher
volumes of sound. Sound that seems normal can be
loud and harmful to your hearing. Take precautions by
adjusting the volume control on your radio to a safe
sound level before your hearing adapts to it.
To help avoid hearing loss or damage:

Adjust the volume control to the lowest setting.

Increase volume slowly until you hear comfortably
and clearly.NOTICE:
Before you add any sound equipment to your
vehicle
-- like a tape player, CB radio, mobile
telephone or two
-way radio -- be sure you
can add what you want. If you can, it's very
important to do it properly. Added sound
equipment may interfere with the operation of
your vehicle's engine, Delphi Delco Electronics
radio or other systems, and even damage them.
Your vehicle's systems may interfere with the
operation of sound equipment that has been
added improperly.
So, before adding sound equipment, check with
your dealer and be sure to check Federal rules
covering mobile radio and telephone units.

4-7
Avoid needless heavy braking. Some people drive
in spurts
-- heavy acceleration followed by heavy
braking
-- rather than keeping pace with traffic.
This is a mistake. Your brakes may not have time to
cool between hard stops. Your brakes will wear out
much faster if you do a lot of heavy braking.
If you keep pace with the traffic and allow realistic
following distances, you will eliminate a lot of
unnecessary braking. That means better braking
and longer brake life.
If your engine ever stops while you're driving, brake
normally but don't pump your brakes. If you do,
the pedal may get harder to push down. If your
engine stops, you will still have some power brake
assist. But you will use it when you brake. Once the
power assist is used up, it may take longer to stop and
the brake pedal will be harder to push.
Anti-Lock Brakes (ABS)
Your vehicle has anti-lock brakes (ABS). ABS is an
advanced electronic braking system that will help
prevent a braking skid.
When you start your engine and begin to drive away,
your anti
-lock brake system will check itself. You may
hear a momentary motor or clicking noise while this test
is going on. This is normal.
If there's a problem with
the anti
-lock brake system,
this warning light will stay
on. See ªAnti
-Lock Brake
System Warning Lightº
in the Index.

4-9
Remember: Anti-lock doesn't change the time you need
to get your foot up to the brake pedal or always decrease
stopping distance. If you get too close to the vehicle in
front of you, you won't have time to apply your brakes
if that vehicle suddenly slows or stops. Always leave
enough room up ahead to stop, even though you have
anti
-lock brakes.
Using Anti
-Lock
Don't pump the brakes. Just hold the brake pedal down
firmly and let anti
-lock work for you. You may feel the
brakes vibrate, or you may notice some noise, but this
is normal.
Braking in Emergencies
With anti-lock, you can steer and brake at the same
time. In many emergencies, steering can help you
more than even the very best braking.
Traction Assist System (Option)
Your vehicle may have a Traction Assist System (TAS)
that limits wheel spin. This is especially useful in
slippery road conditions. The system operates only if it
senses that one or both of the rear wheels are spinning
or beginning to lose traction. When this happens, the
system reduces engine power to limit wheel spin.
This light will come
on when the TAS is
limiting wheel spin.
See ªLow Traction Lightº
in the Index.
You may hear or feel the system working or notice a
lack of accelerator response, but this is normal.

4-10
The Traction Assist System may operate on dry roads
under some conditions. When this happens, you may
notice a reduction in acceleration. This is normal and
doesn't mean there's a problem with your vehicle.
Examples of these conditions include a hard acceleration
in a turn, an abrupt upshift or downshift of the
transmission or driving on rough roads.
If your vehicle is in cruise control when the TAS begins
to limit wheel spin, the cruise control will automatically
disengage. When road conditions allow you to safely
use it again, you may re
-engage the cruise control.
See ªCruise Controlº in the Index.
When the TRACTION
OFF light is on, the TAS
is off and will not limit
wheel spin. Adjust your
driving accordingly.The TRACTION OFF light will come on under the
following conditions:

The Traction Assist System is turned off, either by
pressing the TAS on/off button or turning off the
automatic engagement feature of the TAS.

The transmission is in FIRST (1); TAS will not
operate in this gear. This is normal.

The vehicle is driven on a severely rough road.
When the vehicle leaves the rough surface, slows
down or stops, the light will go off and TAS will be
on again. This is normal.

A Traction Assist System, Anti-Lock Brake System
or engine
-related problem has been detected and the
vehicle needs service.
See ªTraction Off Lightº in the Index.
The Traction Assist System, as delivered from the
factory, will automatically come on whenever you start
your vehicle. To limit wheel spin, especially in slippery
road conditions, you should always leave the system on.
But you can turn the TAS off if you ever need to.
You should turn the TAS off if your vehicle ever gets
stuck in sand, mud or snow and rocking the vehicle is
required. See ªRocking Your Vehicleº in the Index.

4-11
To turn the system on
or off press the TAS
on/off button located
to the left of the of the
steering wheel on the
instrument panel.
If you used the button to turn the system off, the
TRACTION OFF light will come on and stay on. You
can turn the system back on at any time by pressing the
button again. The TRACTION OFF light should go off.If desired, you can change the TAS automatic
engagement feature so that the system will not come
on automatically when the engine is started. To do so:
1. Park vehicle with ignition off and transmission
in PARK (P).
2. Turn the ignition to RUN; do not start the engine.
3. Apply the brake pedal, press the accelerator pedal to
the floor and then press the TAS on/off button and
hold it down for at least six seconds.
4. Release the TAS button and both pedals.
5. Turn off the ignition and wait a few seconds.
The next time you start your vehicle, the TAS will not
automatically come on. You can restore the automatic
feature by using the same procedure. Whether the TAS is
set to come on automatically or not, you can always turn
the system on or off by pressing the TAS on/off button.