2004 GMC SIERRA sensor

Dual Stage Air Bags
If your vehicle has frontal air bags with dual stage
deployment, the amount of restraint will adjust according
to crash severity. For moderate frontal impacts, these
air bags in¯ate at a level less than full deployment. For
more severe frontal impacts, full deployment occurs.
If the front of your vehicle goes straight into a wall that
does not move or deform, the threshold level for the
reduced deployment is about 10 to 16 mph
(16 to 25 km/h), and the threshold level for a full
deployment is about 20 to 25 mph (32 to 40 km/h). The
threshold level can vary, however, with speci®c
vehicle design, so that it can be somewhat above or
below this range.
If your vehicle strikes something that will move or
deform, such as a parked car, the threshold level will be
higher. The air bag is not designed to in¯ate in
rollovers, rear impacts, or in many side impacts because
in¯ation would not help the occupant.
Seat Position Sensors
Vehicle's with dual stage air bags are also equipped
with special sensors which enable the sensing system to
monitor the position of both the driver and passenger
front seats. The seat position sensor provides
information which is used to determine if the air bags
should deploy at a reduced level or at full deployment.
Single Stage Air Bags
If your vehicle has frontal air bags with single stage
deployment and your vehicle goes straight into a wall
that does not move or deform, the threshold level
is about 13 to 16 mph (20 to 25 km/h). The threshold
level can vary, however, with speci®c vehicle design, so
that it can be somewhat above or below this range.
If your vehicle strikes something that will move or
deform, such as a parked car, the threshold level will be
higher. The air bag is not designed to in¯ate in
rollovers, rear impacts, or in many side impacts because
in¯ation would not help the occupant.
What Makes an Air Bag In¯ate?
In an impact of sufficient severity, the air bag sensing
system detects that the vehicle is in a crash. The
sensing system triggers a release of gas from the
in¯ator, which in¯ates the air bag. The in¯ator, air bag,
and related hardware are all part of the air bag
modules inside the steering wheel and in the instrument
panel in front of the right front passenger.
1-74

In many crashes severe enough to in¯ate the air bag,
windshields are broken by vehicle deformation.
Additional windshield breakage may also occur from the
right front passenger air bag.
·Air bags are designed to in¯ate only once. After
they in¯ate, you will need some new parts for
your air bag system. If you do not get them, the air
bag system will not be there to help protect you
in another crash. A new system will include air bag
modules and possibly other parts. The service
manual for your vehicle covers the need to replace
other parts.
·Your vehicle is equipped with electronic frontal
sensors which help the sensing system distinguish
between a moderate and a more severe frontal
impact. Your vehicle is also equipped with a crash
sensing and diagnostic module, which records
information about the frontal air bag system. The
module records information about the readiness of
the system and when the system commands air
bag in¯ation. It records the status of the driver's
safety belt usage in a crash in which the air
bag deploys or a crash in which the air bag nearly
deploys. The module also records speed, engine
rpm, brake and throttle data.
·Let only quali®ed technicians work on your air bag
systems. Improper service can mean that an air
bag system will not work properly. See your dealer
for service.
Notice:If you damage the covering for the driver's
or the right front passenger's air bag, the bag
may not work properly. You may have to replace the
air bag module in the steering wheel or both the
air bag module and the instrument panel for
the right front passenger's air bag. Do not open or
break the air bag coverings.
Air Bag Off Switch
Regular Cab and Extended Cab Models
If your vehicle is a regular cab model or an extended cab
model, it has a switch on the instrument panel that you
can use to turn off the right front passenger's air bag.
1-76

The passenger sensing system will turn off the right
front passenger's frontal air bag under certain
conditions. The driver's air bag is not part of the
passenger sensing system. In addition to the passenger
sensing system, your vehicle also has an air bag off
switch located on the instrument panel.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
passenger's frontal air bag should be enabled (may
in¯ate) or not.
Accident statistics show that children are safer if they
are restrained in the rear rather than the front seat.
General Motors recommends that child restraints
be secured in a rear seat, including an infant riding in a
rear-facing infant seat, a child riding in a forward-facing
child seat and an older child riding in a booster seat.
Never put a child in a rear-facing child restraint in
the right front passenger seat unless the passenger air
bag status indicator shows off. Never put a rear-facing
child restraint in the right front passenger seat unless the
air bag is off. Passenger Air Bag Status Indicator ± United States
Passenger Air Bag
Status Indicator
-Canada
1-82

Servicing Your Air Bag-Equipped
Vehicle
Air bags affect how your vehicle should be serviced.
There are parts of the air bag system in several places
around your vehicle. You don't want the system to
in¯ate while someone is working on your vehicle. Your
dealer and the service manual have information
about servicing your vehicle and the air bag system. To
purchase a service manual, see
Service Publications
Ordering Information on page 7-12.
{CAUTION:
For up to 10 seconds after the ignition key is
turned off and the battery is disconnected, an
air bag can still in¯ate during improper
service. You can be injured if you are close to
an air bag when it in¯ates. Avoid yellow
connectors. They are probably part of the air
bag system. Be sure to follow proper service
procedures, and make sure the person
performing work for you is quali®ed to do so.
The air bag system does not need regular maintenance.
Adding Equipment to Your Air
Bag-Equipped Vehicle
Q:Is there anything I might add to the front of the
vehicle that could keep the air bags from
working properly?
A:Yes. If you add things that change your vehicle's
frame, bumper system, front end sheet metal or
height, they may keep the air bag system
from working properly. Also, the air bag system
may not work properly if you relocate any of the air
bag sensors. 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. See²Customer
Satisfaction Procedure²in the Index.
1-86

;(Parking Lamps):Turning the control to this
position turns on the parking lamps, together with the
following:
·Sidemarker Lamps
·Taillamps
·License Plate Lamps
·Instrument Panel Lights
·Roof Marker Lamps, if equipped
2(Headlamps):Turning the switch to this position
turns on the headlamps, together with the previously
listed lamps and lights.
You can switch your headlamps from high to low-beam
by pushing the turn signal/high-beam lever towards
the instrument panel.
A circuit breaker protects your headlamps. If you have
an electrical overload, your headlamps will ¯icker on and
off. Have your headlamp wiring checked right away if
this happens.
Automatic Headlamp System
When it is dark enough outside, your automatic
headlamp system will turn on your headlamps at the
normal brightness along with other lamps such as
the taillamps, sidemarker, parking lamps and the
instrument panel lights. The radio lights will also be dim.
Your vehicle is equipped with a light sensor located
on the top of the instrument panel in the defroster grille.
Be sure it is not covered, or the system will be on
whenever the ignition is on.
The system may also turn on your headlamps when
driving through a parking garage, heavy overcast
weather or a tunnel. This is normal.
There is a delay in the transition between the daytime
and nighttime operation of the Daytime Running
Lamps (DRL) and the automatic headlamp systems so
that driving under bridges or bright overhead street
lights does not affect the system. The DRL and
automatic headlamp system will only be affected when
the light sensor sees a change in lighting lasting
longer than the delay.
3-15

If you start your vehicle in a dark garage, the automatic
headlamp system will come on immediately. Once
you leave the garage, it will take approximately
one minute for the automatic headlamp system to
change to DRL if it is bright enough outside. During that
delay, your instrument panel cluster may not be as
bright as usual. Make sure your instrument panel
brightness control is in the full bright position. See
ªInstrument Panel Brightness Controlº under
Interior
Lamps on page 3-19.
To idle your vehicle with the automatic headlamp
system off, turn the control to the off position.
You may be able to turn off your Automatic Headlamp
System. See ªDaytime Running Lamps (DRL)º later
in this section for more information.
As with any vehicle, you should turn on the regular
headlamp system when you need them.
Lamps On Reminder
A reminder chime will sound when your headlamps or
parking lamps are manually turned on and your ignition is
off, in LOCK, ACCESSORY, or your door is open. To
disable the chime, turn the light off then back on.
Daytime Running Lamps
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.
The DRL system will come on when the following
conditions are met:
·The ignition is on
·The exterior lamps control is in AUTO
·The automatic transmission is not in PARK (P)
·The light sensor determines it is daytime
When the DRL system is on, only your DRL lamps will
be on. The taillamps, sidemarker and other lamps
won't be on. The instrument panel won't be lit up either.
When it begins to get dark, the automatic headlamp
system will switch from DRL to the headlamps or the last
chosen headlamp setting that was used.
When you turn the headlamp switch off, the headlamps
will go off, and your DRL lamps will illuminate,
provided it is not dark outside.
3-16

The passenger's temperature setting can be set to
match the driver's temperature setting by pressing and
holding the AUTO button for four seconds. Both the
driver and passenger arrows will be displayed.
Automatic Operation
AUTO (Automatic):When automatic operation is
active the system will control the inside temperature, the
air delivery, and the fan speed.
Use the steps below to place the entire system in
automatic mode:
1. Press the AUTO button.
When AUTO is selected, the display will change to
show the current driver's set temperature, delivery
mode and fan speed. Press the AUTO button again
within ®ve seconds to display the passenger's set
temperature.
If the driver and passenger's temperature settings
are not the same, the opposite side temperature
setting will be displayed for an additional
®ve seconds. To make the passenger's temperature
the same as the driver's press and hold the
AUTO button for about four seconds.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
40ÉF (4ÉC). The air inlet will normally be set to
outside air. If it's hot outside, the air inlet may
automatically switch to recirculate inside air to help
quickly cool down your 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 74ÉF (23ÉC)
temperature setting and allow about 20 minutes
for the system to regulate. Turn the driver's or
passenger's side temperature knob to adjust the
temperature setting as necessary. If you choose the
temperature setting of 60ÉF (15ÉC) the system
will remain at the maximum cooling setting. If you
choose the temperature setting of 90ÉF (32ÉC)
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 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 your headlamps.
3-27

Safety Belt Reminder Light
When the key is turned to RUN or START, 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.
If the driver's belt is already buckled, neither the chime
nor the light will come on.
Air Bag Readiness Light
There is an air bag readiness light on the instrument
panel cluster, which shows the air bag symbol.
The system checks the air bag's electrical system for
malfunctions. The light tells you if there is an electrical
problem. The system check includes the air bag
sensors, the air bag modules, the passenger sensing
system (if equipped), the wiring and the crash sensing
and diagnostic module. For more information on the
air bag system, see
Air Bag Systems on page 1-70.
This light will come on
when you start your
vehicle, and it will ¯ash for
a few seconds. Then
the light should go out.
This means the system is
ready.
If the air bag readiness light stays on after you start the
vehicle or comes on when you are driving, your air
bag system may not work properly. Have your vehicle
serviced right away.
3-36