engine GMC SIERRA 2007 Service Manual

The recirculation mode cannot be used with oor,
defog, or defrost modes. If recirculation is selected
with one of those modes, the indicator light will ash
three times and then 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.
The recirculation mode can be turned off by
pressing the outside air button, or by turning off
the ignition.
;(Outside Air):Press this button to turn on
the outside air mode. When this mode is selected,
air from outside the vehicle will circulate
throughout your vehicle. An indicator light on the
button will come on to let you know that it is
activated. The outside air mode can be used
with all modes, but it cannot be used with
the recirculation mode.
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 let you know that the air
conditioning has been activated.
Pressing this button when the outside temperature
is too cool for air conditioning makes the air
conditioning indicator ash three times and then
turn off to let you know 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 turns
off to let you know 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 the vehicle to cool down. It also
helps the system to operate more efficiently.
The air conditioning system removes moisture from
the air, so you might notice a small amount of
water dripping underneath the vehicle while idling
or after turning off the engine. This is normal.
242

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 the windshield.
Use the mode up and down arrows to select the
defog or defrost modes.
-(Defog):Press this button 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):Press this button 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 your 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.
Rear Window Defogger
The rear window defogger uses a warming grid to
remove fog from the rear window.
<(Rear Window Defogger):If your vehicle
has this feature, press this button to turn the
defogger on or off. It will automatically turn
off several minutes after it has been activated.
The defogger can also be turned off by turning the
engine off. Do not drive the vehicle until all the
windows are clear.
244

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. SeeDIC Warnings and Messages
on page 279for more information.
246

Instrument Panel Cluster
Your instrument cluster is designed to let you know at a glance how your vehicle is running. You will
know how fast you are going, about how much fuel you have and many other things you will need to know
to drive safely and economically. If your vehicle has the DURAMAX
®Diesel engine, see the DURAMAX®
Diesel manual for more information.
United States Light Duty Premium version shown. Canada, Uplevel, Base, Heavy Duty Clusters similar.
247

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).
Engine Hour Meter Display
The Driver Information Center (DIC) can also
display the number of hours the engine has run.
To display the engine hours, turn the ignition
off, press and hold the reset button for at least
four seconds. The hour meter will be displayed for
up to 30 seconds, or until the ignition is turned
on. SeeDIC Operation and Displays (With
DIC Buttons) on page 268orDIC Operation and
Displays (Without DIC Buttons) on page 275
for more information.
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 voltmeter, 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.
SeeDIC Operation and Displays (With DIC
Buttons) on page 268orDIC Operation and
Displays (Without DIC Buttons) on page 275for
more information.
Tachometer
Your tachometer displays the engine speed in
revolutions per minute (rpm). See “Grade Braking
(Allison Transmission
®)” underTow/Haul Mode
on page 144for more information.
248

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 250for more on this, including
important safety information.
Charging System Light
If this light comes on
when the engine is
running, there could be
a problem with the
charging system.
This light will also stay on while the key is in RUN
until the engine is started.
If the light stays on after starting the engine it
could indicate a problem with the generator drive
belt, or some other charging system problem.
Have it checked right away. Driving while this light
is on could drain the battery.
If you must drive a short distance with this light
on, it helps to turn off all of the electrical
accessories, such as the radio and the blower.
254

Voltmeter Gage
Your vehicle may have
a voltmeter gage.
When the ignition is in RUN, this gage indicates
the battery voltage.
When the engine is running, this gage shows the
condition of the charging system. The gage
may transition from a higher to lower or a lower to
higher reading, this is normal. If the vehicle is
operating outside the normal operating range, thecharging system light will come on. SeeCharging
System Light on page 254for more information.
The voltmeter gage may also read lower when in
fuel economy mode. This is normal.
Readings outside the normal operating range may
also occur when a large number of electrical
accessories are operating in the vehicle and the
engine is left idling 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 maximum power.
You can only drive for a short time with the readings
outside the normal operating range. If you must
drive, turn off all unnecessary accessories.
Readings outside the normal operating range
indicate a possible problem in the electrical system.
Have the vehicle serviced as soon as possible.
255

Anti-Lock Brake System
Warning Light
With the Anti-Lock
Brake System (ABS),
this light will come on
when you start your
engine and may stay on
for several seconds.
That is normal. If the light does not come on then,
have it xed so it will be ready to warn you if
there is a problem.If the light stays on, or comes on when you are
driving, your vehicle needs service. A chime
will sound when the light stays on. If the regular
brake system warning light is not on, you still have
brakes, but you do not have ABS. If the regular
brake system warning light is also on you do
not have ABS and there is a problem with your
regular brakes. In addition to both lights, you
will also hear a chime sound on the rst
occurrence of a problem and each time the
vehicle is shut off and then restarted. SeeBrake
System Warning Light on page 256.
The ABS warning light should come on briey
when you turn the ignition key to RUN. If the light
does not come on then, have it xed so it will
be ready to warn you if there is a problem.
257

StabiliTrak®Indicator Light
If equipped, this warning
light should come on
briey when the engine
is started.
If the warning light does not come on then, have it
xed so it will be ready to warn you if there is a
problem. If it stays on, or comes on when you are
driving, there may be a problem with your
StabiliTrak
®system and your vehicle may need
service. When this warning light is on, the system
is off and will not limit wheel spin. Adjust your
driving accordingly.
This light will also ash when the StabiliTrak
®
system is active.
If the StabiliTrak
®system warning light comes on
and stays on for an extended period of time
when the system is turned on, your vehicle needs
service. SeeStabiliTrak
®System on page 381
for more information.
Engine Coolant Temperature Gage
This gage shows the engine coolant temperature.
It also provides an indicator of how hard your
vehicle is working. During a majority of the
operation, the gage will read 210°F (100°C) or
less. If you are pulling a load or going up hills, it is
normal for the temperature to uctuate and go
over the 235°F (113°C) mark. However, if the gage
reaches the 260°F (125°C) mark, it indicates
that the cooling system is working beyond
its capacity.
SeeEngine Overheating on page 516.
United StatesCanada
258

Malfunction Indicator Lamp
Check Engine Light
Your vehicle has a
computer which
monitors operation of the
fuel, ignition, and
emission control
systems.
This system is called OBD II (On-Board
Diagnostics-Second Generation) and is intended
to assure that emissions are at acceptable
levels for the life of the vehicle, helping to produce
a cleaner environment. The check engine light
comes on to indicate that there is a problem and
service is required. Malfunctions often will be
indicated by the system before any problem is
apparent. This may prevent more serious damage
to your vehicle. This system is also designed to
assist your service technician in correctly
diagnosing any malfunction.Notice:If you keep driving your vehicle with
this light on, after awhile, the emission controls
might not work as well, your vehicle’s fuel
economy might not be as good, and the engine
might not run as smoothly. This could lead
to costly repairs that might not be covered by
your warranty.
Notice:Modications made to the engine,
transmission, exhaust, intake, or fuel system
of your vehicle or the replacement of the
original tires with other than those of the same
Tire Performance Criteria (TPC) can affect
your vehicle’s emission controls and can cause
this light to come on. Modications to these
systems could lead to costly repairs not
covered by your warranty. This could also
result in a failure to pass a required Emission
Inspection/Maintenance test. SeeAccessories
and Modifications on page 486.
260