light GMC YUKON 2008 Repair Manual

Temperature Control:Rotate the thumbwheels up or
down to increase or decrease the temperature on
the driver’s side or the passenger side of the vehicle for
the dual zone system, if equipped. Otherwise, turn
the center knob clockwise or counterclockwise to
increase or decrease the temperature inside the vehicle.
#(Air Conditioning):Press this button on the left
knob to turn the air conditioning system on or off. When
A/C is pressed, an indicator light comes on to show
that the air conditioning has been activated.
On hot days, open the windows to let hot inside air
escape; then close them. This helps to reduce the time
it takes for your vehicle to cool down. It also helps
the system to operate more efficiently.
The air conditioning system removes moisture from the
air, so a small amount of water might drip underneath
the vehicle while idling or after turning off the engine.
This is normal.
Defogging and Defrosting
Fog on the inside of the windows is a result of high
humidity (moisture) condensing on the cool window
glass. This can be minimized if the climate control
system is used properly. There are two modes to clear
fog or frost from your windshield. Turn the right knob
clockwise to select the defog or defrost mode.
-(Defog):The defog mode is used to clear the
windows of fog or moisture and warm the passengers.
This mode directs air to the windshield, oor outlets,
and side window vents. When this mode is selected, the
system turns off recirculation and runs the air
conditioning compressor unless the outside temperature
is close to freezing. The recirculation mode cannot be
selected while in the defog mode. Do not drive the
vehicle until all the windows are clear.
0(Defrost):The defrost mode is used to remove fog
or frost from the windshield more quickly. This mode
directs a portion of the air to the windshield and
side window vents and some to the oor vents. In this
mode, the system will automatically force outside air into
the vehicle. The recirculation mode cannot be selected
while in the defrost mode. The air conditioning
compressor will run automatically in this setting, unless
the outside temperature is close to freezing. Do not
drive the vehicle until all the windows are clear.
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When AUTO is selected, the air conditioning
operation and air inlet will be automatically
controlled. The air conditioning compressor will run
when the outside temperature is over about
40°F (4°C). The air inlet will normally be set to
outside air. If it is hot outside, the air inlet may
automatically switch to recirculate inside air to help
quickly cool down the vehicle. The light on the
button will illuminate in recirculation.
2. Set the driver’s and passenger’s temperature.
To nd your comfort setting, start with a 74°F (23°C)
temperature setting and allow about 20 minutes
for the system to regulate. Use the driver’s or
passenger’s temperature buttons to adjust the
temperature setting as necessary. If you choose the
temperature setting of 60°F (15°C), the system
will remain at the maximum cooling setting. If you
choose the temperature setting of 90°F (32°C),
the system will remain at the maximum heat setting.
Choosing either maximum setting will not cause
the vehicle to heat or cool any faster.Be careful not to cover the solar sensor located on the
top of the instrument panel near the windshield. This
sensor regulates air temperature based on sun load and
also turns on the headlamps. For more information on
the solar sensor, see “Sensors” later in this section.
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 engine coolant
temperature. Pressing the fan switch will override this
delay and change the fan to a selected speed.
O(On/Off):Press this button to turn off the climate
control system. Outside air will still enter the vehicle, and
will be directed to the oor. This direction can be
changed by pressing the mode button. Recirculation
can be selected once vent or bi-level mode has
been selected. The temperature can also be adjusted
using either temperature button. If the air delivery mode
or temperature settings are adjusted with the system
off, the display will illuminate briey to show you
the settings and then return off. Press the on/off button
or the up down arrows on the fan switch, the defrost
button, AUTO button, or the air conditioning button
to turn the system on when it is off.
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Manual Operation
You may manually adjust the air delivery mode or fan
speed.
y9 z(Fan):The buttons with the fan symbols
allow you to manually adjust the fan speed. Press the
up arrow to increase fan speed and the down arrow
to decrease fan speed.
Pressing one of these buttons when the system is off
will turn the system on. Pressing one of these buttons
when in automatic control will place the fan under
manual control. The fan setting will remain displayed
and the AUTO light will turn off. The air delivery
mode will remain under automatic control.
yNz(Mode):Press the mode up and down
buttons to manually change the direction of the airow
in the vehicle. Repeatedly press the button until the
desired mode appears on the display. Pressing one of
these buttons when the system is off will change air
delivery mode without turning the system on. Pressing
one of these buttons when in automatic control will place
the mode under manual control.The air delivery mode setting will be displayed and the
AUTO light will turn off. The fan will remain under
automatic control.
H(Vent):This setting will deliver air to the instrument
panel outlets.
)(Bi-Level):This mode directs half of the air to the
instrument panel outlets and half to the oor outlets.
The ow can be divided between vent and oor outlets
depending upon where the knob is placed between
the settings. A little air is directed towards the windshield
and side window outlets. Cooler air is directed to the
upper outlets and warmer air to the oor outlets.
6(Floor):This mode directs most of the air to the
oor outlets, with some of the air directed to the
windshield, side window outlets, and second row oor
outlets. In this mode, the system automatically
selects outside air.
-(Defog):See “Defogging and Defrosting” later in
this section.
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@(Recirculation):Press this button to turn the
recirculation mode on. When the button is pressed, an
indicator light comes on.
This mode keeps outside air from entering the vehicle.
It can be used to reduce outside air and prevent
odors from entering the vehicle. Recirculation may also
help cool the air inside the vehicle more quickly once
the temperature inside the vehicle is less than the
outside temperature.
The recirculation mode cannot be used with oor,
defrost, or defogging modes. If you try to select
recirculation in one of those modes, the indicator will
ash three times and turn off. The air conditioning
compressor will also come on when this mode is
activated. While in recirculation mode the windows may
fog when the weather is cold and damp. To clear the
fog, select either the defog or defrost mode and increase
the fan speed. Recirculation mode can be turned off
by pressing the button again, or turning off the engine.Air Conditioning
#
(Air Conditioning):Press this button to turn the
air conditioning (A/C) compressor on and off. When
air conditioning is selected, an indicator light comes on
to show that the air conditioning has been activated.
Pressing this button when the outside temperature is too
cool for air conditioning will make the air conditioning
indicator ash three times and then turn off to show that
the air conditioning mode is not available. If the air
conditioning is on and the outside temperature drops
below a temperature which is too cool for air
conditioning to be effective, the air conditioning light will
turn off to show that the air conditioning mode has
been canceled.
On hot days, open the windows long enough to let hot
inside air escape. This helps to reduce the time it
takes for your vehicle to cool down. It also helps the
system to operate more efficiently.
The air conditioning system removes moisture from the
air, so a small amount of water might drip underneath
the vehicle while idling or after turning off the engine.
This is normal.
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Warning Lights, Gages, and
Indicators
This part describes the warning lights and gages on
your vehicle. The pictures help to locate them.
Warning lights and gages can signal that something is
wrong before it becomes serious enough to cause
an expensive repair or replacement. Paying attention to
the warning lights and gages could also save you or
others from injury.
Warning lights come on when there may be or is a
problem with one of your vehicle’s functions. As
the details show on the next few pages, some warning
lights come on briey when you start the engine just
to let you know they are working. If you are familiar with
this section, you should not be alarmed when this
happens.Gages can indicate when there may be or is a problem
with one of your vehicle’s functions. Often gages
and warning lights work together to let you know when
there is a problem with your vehicle.
When one of the warning lights comes on and stays on
as you are driving, or when one of the gages shows
there may be a problem, check the section that tells you
what to do about it. Please follow this manual’s
advice. Waiting to do repairs can be costly and even
dangerous. So please get to know your vehicle’s
warning lights and gages. They can be a big help.
Your vehicle also has a Driver Information Center (DIC)
that works along with warning lights and gages. See
DIC Warnings and Messages on page 3-64for
more information.
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Speedometer and Odometer
Your speedometer lets you see your speed in both
miles per hour (mph) and kilometers per hour (km/h).
Your odometer shows how far your vehicle has
been driven, in either miles (used in the United States)
or kilometers (used in Canada).
Trip Odometer
The trip odometer can tell you how far your vehicle has
been driven since you last set the trip odometer to zero.
Press the reset button, located on the instrument panel
cluster next to the trip odometer display, to toggle
between the trip odometer and the regular odometer.
Holding the reset button for approximately one second
while the trip odometer is displayed will reset it.
To display the odometer reading with the ignition off,
press the reset button.
Tachometer
Your tachometer displays the engine speed in
revolutions per minute (rpm).
Safety Belt Reminders
Safety Belt Reminder Light
When the engine is started, a chime will come on for
several seconds to remind people to fasten their safety
belts, unless the driver’s safety belt is already buckled.
The safety belt light will
also come on and stay on
for several seconds, then it
will ash for several more.
This chime and light is repeated if the driver remains
unbuckled and the vehicle is in motion. If the driver’s belt
is already buckled, neither the chime nor the light will
come on.
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Passenger Safety Belt Reminder Light
Several seconds after the engine is started, a chime
will sound for several seconds to remind the front
passenger to buckle their safety belt. This would only
occur if the passenger airbag is enabled. SeePassenger
Sensing System on page 1-85for more information.
The passenger safety belt light, located on the
instrument panel, will come on and stay on for several
seconds and then ash for several more.
This chime and light are
repeated if the passenger
remains unbuckled and
the vehicle is in motion.
If the passenger’s safety belt is buckled, neither the
chime nor the light will come on.
Airbag Readiness Light
There is an airbag readiness light on the instrument
panel cluster, which shows the airbag symbol. The
system checks the airbag’s electrical system for
malfunctions. The light tells you if there is an electrical
problem. The system check includes the airbag
sensor, the pretensioners, the airbag modules, the
wiring and the crash sensing and diagnostic module.
For more information on the airbag system, seeAirbag
System on page 1-76.
This light will come on
when you start your
vehicle, and it will ash for
a few seconds. The
light should go out and the
system is ready.
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If the airbag readiness light stays on after you start the
vehicle or comes on when you are driving, your
airbag system may not work properly. Have your vehicle
serviced right away.
{CAUTION:
If the airbag readiness light stays on after you
start your vehicle, it means the airbag system
may not be working properly. The airbags in
your vehicle may not inate in a crash, or they
could even inate without a crash. To help avoid
injury to yourself or others, have your vehicle
serviced right away if the airbag readiness light
stays on after you start your vehicle.
The airbag readiness light should ash for a few
seconds when you start the engine. If the light does not
come on then, have it xed immediately. If there is a
problem with the airbag system, an airbag Driver
Information Center (DIC) message may also come on.
SeeDIC Warnings and Messages on page 3-64for
more information.
Passenger Airbag Status Indicator
Your vehicle has the passenger sensing system.
Your overhead console has a passenger airbag status
indicator.
When you start the vehicle, the passenger airbag status
indicator will light ON and OFF, or the symbol for on
and off, for several seconds as a system check.
Then, after several more seconds, the status indicator
will light either ON or OFF, or either the on or off symbol
to let you know the status of the right front passenger’s
frontal airbag.United States
Canada
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If, after several seconds, both status indicator lights
remain on, or if there are no lights at all, there may be a
problem with the lights or the passenger sensing
system. See your dealer/retailer for service.
{CAUTION:
If the airbag readiness light in the instrument
panel cluster ever comes on and stays on, it
means that something may be wrong with the
airbag system. If this ever happens, have the
vehicle serviced promptly, because an
adult-size person sitting in the right front
passenger’s seat may not have the protection
of the airbag(s). SeeAirbag Readiness Light
on page 3-40for more on this, including
important safety information.
Charging System Light
This light will come on
briey when you turn on
the ignition, but the engine
is not running, as a
check to show you it is
working.
It should go out once the engine is running. If it stays
on, or comes on while you are driving, you may have a
problem with the charging system. A charging system
Driver Information Center (DIC) message may also
appear. SeeDIC Warnings and Messages on page 3-64
for more information. This light could indicate that you
have problems with a generator drive belt, or another
electrical problem. Have it checked right away. If
you must drive a short distance with the light on, be
certain to turn off all your accessories, such as the radio
and air conditioner.
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Voltmeter Gage
When your engine is not
running, but the ignition is
on, this gage shows
the battery’s state of
charge in DC volts.
When the engine is running, the gage shows the
condition of the charging system. The charging system
regulates voltage based on the state of the battery
for improved fuel economy and battery life. The gage
may transition from a higher to lower or a lower to higher
reading, this is normal. Readings between the low
and high warning zones indicate the normal operating
range. The gage may also read low during the fuel
economy mode, this is normal.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 full power. If
there is a problem with the battery charging system,
this light will come on or the SERVICE BATTERY
CHARGING SYSTEM DIC message will display. See
DIC Warnings and Messages on page 3-64and
Charging System Light on page 3-43for more
information.
Brake System Warning Light
With the ignition on, the brake system warning light will
come on when you set the parking brake. If you try to
drive with the parking brake engaged, a chime will sound
when the vehicle speed is greater than 5 mph (8 km/h).
Your vehicle’s hydraulic brake system is divided into
two parts. If one part is not working, the other part can
still work and stop you. For good braking, though,
you need both parts working well.
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