2008 CHEVROLET IMPALA sensor

When Should an Airbag Inate?
Frontal airbags are designed to inate in moderate to
severe frontal or near-frontal crashes to help reduce the
potential for severe injuries mainly to the driver’s or
right front passenger’s head and chest. However, they
are only designed to inate if the impact exceeds a
predetermined deployment threshold. Deployment
thresholds are used to predict how severe a crash is
likely to be in time for the airbags to inate and
help restrain the occupants.
Whether your frontal airbags will or should deploy is not
based on how fast your vehicle is traveling. It depends
largely on what you hit, the direction of the impact,
and how quickly your vehicle slows down.
Frontal airbags may inate at different crash speeds.
For example:
If the vehicle hits a stationary object, the airbags
could inate at a different crash speed than if the
vehicle hits a moving object.
If the vehicle hits an object that deforms, the
airbags could inate at a different crash speed than
if the vehicle hits an object that does not deform.
If the vehicle hits a narrow object (like a pole), the
airbags could inate at a different crash speed
than if the vehicle hits a wide object (like a wall).
If the vehicle goes into an object at an angle, the
airbags could inate at a different crash speed
than if the vehicle goes straight into the object.Thresholds can also vary with specic vehicle design.
Frontal airbags are not intended to inate during vehicle
rollovers, rear impacts, or in many side impacts.
In addition, your vehicle has dual-stage frontal airbags.
Dual-stage airbags adjust the restraint according to
crash severity. Your vehicle has electronic frontal
sensors, which help the sensing system distinguish
between a moderate frontal impact and a more severe
frontal impact. For moderate frontal impacts, dual-stage
airbags inate at a level less than full deployment.
For more severe frontal impacts, full deployment occurs.
Your vehicle may or may not have roof-rail airbags.
SeeAirbag System on page 1-54. Roof-rail airbags are
intended to inate in moderate to severe side crashes.
Roof-rail airbags will inate if the crash severity is above
the system’s designed threshold level. The threshold
level can vary with specic vehicle design.
Roof-rail airbags are not intended to inate in frontal
impacts, near-frontal impacts, rollovers, or rear impacts.
Both roof-rail airbags will deploy when either side of
the vehicle is struck.
In any particular crash, no one can say whether an
airbag should have inated simply because of the
damage to a vehicle or because of what the repair costs
were. For frontal airbags, ination is determined by
what the vehicle hits, the angle of the impact, and how
quickly the vehicle slows down. For roof-rail airbags,
deployment is determined by the location and severity of
the side impact.
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Passenger Sensing System
Your vehicle has a passenger sensing system for the
right front passenger’s position. The passenger
airbag status indicator will be visible on the instrument
panel when you start your vehicle.
The words ON and OFF, or the symbol for on and off,
will be visible during the system check. If you are
using remote start to start your vehicle from a distance,
if equipped, you may not see the system check.
When the system check is complete, either the word
ON or the word OFF, or the symbol for on or the symbol
for off, will be visible. SeePassenger Airbag Status
Indicator on page 3-32.The passenger sensing system will turn off the right
front passenger’s frontal airbag under certain conditions.
The driver’s airbags are not part of the passenger
sensing system.
The passenger sensing system works with sensors that
are part of the right front passenger’s seat and safety
belt. The sensors are designed to detect the presence of
a properly-seated occupant and determine if the right
front passenger’s frontal airbag should be enabled
(may inate) or not.
Accident statistics show that children are safer if they
are restrained in the rear rather than the front seat.
We recommend that children be secured in a rear seat,
including: an infant or a child riding in a rear-facing
child restraint; a child riding in a forward-facing child
seat; an older child riding in a booster seat; and children,
who are large enough, using safety belts.
A label on your sun visor says, “Never put a rear-facing
child seat in the front.” This is because the risk to the
rear-facing child is so great, if the airbag deploys. United States
Canada
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Adding Equipment to Your
Airbag-Equipped Vehicle
Q:Is there anything I might add to or change
about the vehicle that could keep the airbags
from working properly?
A:Yes. If you add things that change your vehicle’s
frame, bumper system, height, front end or side
sheet metal, they may keep the airbag system from
working properly. Changing or moving any parts
of the front seats, safety belts, the airbag sensing
and diagnostic module, steering wheel, instrument
panel, roof-rail airbag modules, ceiling headliner
or pillar garnish trim, front sensors, or airbag wiring
can affect the operation of the airbag system.
In addition, your vehicle has a passenger sensing
system for the right front passenger’s position,
which includes sensors that are part of the
passenger’s seat. The passenger sensing system
may not operate properly if the original seat trim
is replaced with non-GM covers, upholstery or trim,
or with GM covers, upholstery or trim designed
for a different vehicle. Any object, such as an
aftermarket seat heater or a comfort enhancing pad
or device, installed under or on top of the seatfabric, could also interfere with the operation of the
passenger sensing system. This could either
prevent proper deployment of the passenger
airbag(s) or prevent the passenger sensing system
from properly turning off the passenger airbag(s).
SeePassenger Sensing System on page 1-62.
If you have any questions about this, you should
contact Customer Assistance before you modify
your vehicle. The phone numbers and addresses for
Customer Assistance are in Step Two of the
Customer Satisfaction Procedure in this manual.
SeeCustomer Satisfaction Procedure on page 7-2.
Q:Because I have a disability, I have to get
my vehicle modied. How can I nd out whether
this will affect my airbag system?
A:If you have questions, call Customer Assistance.
The phone numbers and addresses for Customer
Assistance are in Step Two of the Customer
Satisfaction Procedure in this manual. See
Customer Satisfaction Procedure on page 7-2.
In addition, your dealer/retailer and the service manual
have information about the location of the airbag
sensors, sensing and diagnostic module and airbag
wiring.
1-67

Daytime Running Lamps (DRL)/
Automatic Headlamp System
Daytime Running Lamps (DRL) can make it easier for
others to see the front of your vehicle during the day.
DRL can be helpful in many different driving conditions,
but they can be especially helpful in the short periods
after dawn and before sunset. Fully functional daytime
running lamps are required on all vehicles rst sold
in Canada.
A light sensor on top of the instrument panel makes the
DRL work, so be sure it is not covered.
The DRL system’s automatic headlamp control will
make the low-beam headlamps come on at a reduced
brightness when the following conditions are met:
The ignition is in the ON/RUN position.
The exterior lamps control is in AUTO.
The engine is running.
When the DRL are on, only the low-beam headlamps, at
a reduced level of brightness, will be on. The headlamps,
taillamps, sidemarker, and other lamps will not be on.
The instrument panel and cluster will also not be lit.When it is dark enough outside, the low-beam
headlamps will turn off and the headlamps and parking
lamps will turn on. The other lamps that come on
with the headlamps will also come on.
When it is bright enough outside, the headlamps will go
off and the DRL will come on.
As with any vehicle, you should turn on the regular
headlamp system when it is needed.
Fog Lamps
-(Fog Lamps):If your vehicle has fog lamps,
the control is located on the exterior lamps control.
The exterior lamps control is located on the instrument
panel to the left of the steering column.
The ignition must be in the ON/RUN position for the
fog lamps to come on.
Press the exterior lamps button to turn the fog lamps on
or off. A light will come on in the instrument panel
cluster.
When the headlamps are changed to high-beam, the
fog lamps also go off.
Some localities have laws that require the headlamps to
be on along with the fog lamps.
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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 1-54.
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.
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 3-52for more information.
3-31

SERVICE A/C (Air Conditioning)
SYSTEM
This message displays when the electronic sensors that
control the air conditioning and heating systems are
no longer working. Have the climate control system
serviced by your dealer/retailer if you notice a drop in
heating and air conditioning efficiency.
SERVICE AIR BAG
This message displays when there is a problem with the
airbag system. Have your vehicle serviced by your
dealer/retailer immediately. SeeAirbag Readiness Light
on page 3-31for more information.
SERVICE BATTERY CHARGING
SYSTEM
This message displays when there is a problem with the
generator and battery charging systems. Driving with
this problem could drain the battery. Turn off all
unnecessary accessories. Stop and turn off the vehicle
as soon as it is safe to do so. Have the electrical
system checked by your dealer/retailer immediately.
SERVICE BRAKE SYSTEM
This message displays when service is required on the
brake system. Have the brake system serviced by
your dealer/retailer as soon as possible. The brake
system warning light also appears on the instrument
panel cluster when this message appears on the DIC.
SeeBrake System Warning Light on page 3-34.
SERVICE POWER STEERING
This message displays when a problem is detected with
the power steering system. When this message is
displayed, you may notice that the effort required to
steer the vehicle increases or feels heavier, but you will
still be able to steer the vehicle. Have your vehicle
serviced by your dealer/retailer immediately.
SERVICE STABILITRAK
If your vehicle has Electronic Stability Control (ESC),
this message displays if there has been a problem
detected with ESC. The ESC/TCS light also appears on
the instrument panel cluster. SeeElectronic Stability
Control on page 4-7for more information.
If this message turns on while you are driving, pull off the
road as soon as possible and stop carefully. Try resetting
the system by turning the ignition off and then back on.
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STARTING DISABLED SERVICE
THROTTLE
This message displays if the starting of the engine is
disabled due to the electronic throttle control system.
Have your vehicle serviced by your dealer/retailer
immediately.
This message only appears while the ignition is in
ON/RUN, and will not disappear until the problem is
resolved.
This message cannot be acknowledged.
THEFT ATTEMPTED
This message displays if the content theft-deterrent
system has detected a break-in attempt while you were
away from your vehicle. SeeContent Theft-Deterrent
on page 2-18for more information.
TIGHTEN GAS CAP
This message may be displayed if the gas cap is not
on, or is not fully tightened. Check the gas cap to ensure
that it is on properly. SeeFilling the Tank on page 5-10
for more information.
TIRE LEARNING ACTIVE
This message displays when the Tire Pressure Monitor
System (TPMS) is re-learning the tire positions on
your vehicle. The tire positions must be re-learned after
rotating the tires or after replacing a tire or sensor.
SeeTire Inspection and Rotation on page 5-68,
Tire Pressure Monitor System on page 5-63, and
Inflation - Tire Pressure on page 5-61for more
information.
TRACTION CONTROL OFF
If your vehicle has the Traction Control System (TCS),
this message displays when the TCS turns off. See
Traction Control System (TCS) on page 4-6for more
information.
This message only displays while the ignition is in
ON/RUN and disappears after 10 seconds, unless it is
acknowledged or an urgent warning appears.
3-58

Tire Pressure Monitor System
The Tire Pressure Monitor System (TPMS) uses radio
and sensor technology to check tire pressure levels.
The TPMS sensors monitor the air pressure in
your vehicle’s tires and transmit tire pressure readings
to a receiver located in the vehicle.
Each tire, including the spare (if provided), should be
checked monthly when cold and inated to the ination
pressure recommended by the vehicle manufacturer
on the vehicle placard or tire ination pressure
label. (If your vehicle has tires of a different size than
the size indicated on the vehicle placard or tire ination
pressure label, you should determine the proper tire
ination pressure for those tires.)
As an added safety feature, your vehicle has been
equipped with a tire pressure monitoring system (TPMS)
that illuminates a low tire pressure telltale when one
or more of your tires is signicantly under-inated.
Accordingly, when the low tire pressure telltale
illuminates, you should stop and check your tires as
soon as possible, and inate them to the proper
pressure. Driving on a signicantly under-inated tire
causes the tire to overheat and can lead to tire failure.
Under-ination also reduces fuel efficiency and tire
tread life, and may affect the vehicle’s handling
and stopping ability.Please note that the TPMS is not a substitute for proper
tire maintenance, and it is the driver’s responsibility to
maintain correct tire pressure, even if under-ination has
not reached the level to trigger illumination of the
TPMS low tire pressure telltale.
Your vehicle has also been equipped with a TPMS
malfunction indicator to indicate when the system is not
operating properly. The TPMS malfunction indicator
is combined with the low tire pressure telltale. When the
system detects a malfunction, the telltale will ash for
approximately one minute and then remain continuously
illuminated. This sequence will continue upon
subsequent vehicle start-ups as long as the malfunction
exists.
When the malfunction indicator is illuminated, the
system may not be able to detect or signal low tire
pressure as intended. TPMS malfunctions may occur for
a variety of reasons, including the installation of
replacement or alternate tires or wheels on the vehicle
that prevent the TPMS from functioning properly.
Always check the TPMS malfunction telltale after
replacing one or more tires or wheels on your vehicle to
ensure that the replacement or alternate tires and
wheels allow the TPMS to continue to function properly.
SeeTire Pressure Monitor Operation on page 5-64,
for additional information.
5-63