2002 JEEP LIBERTY IAC

is located on the back side of each vertical member of
the radiator support.
²Passenger Airbag- The passenger airbag is
located on the instrument panel, beneath the passen-
ger airbag door on the instrument panel above the
glove box on the passenger side of the vehicle.
²Passenger Knee Blocker- The passenger knee
blocker is a structural reinforcement that is integral
to and concealed within the glove box door.
²Seat Belt Tensioner- The seat belt tensioner
is integral to the driver side front seat belt retractor
unit on vehicles equipped with dual front airbags.
²Side Impact Airbag Control Module-Two
Side Impact Airbag Control Modules (SIACM) are
used on vehicles with the optional side curtain air-
bags, one left side and one right side. One SIACM is
located behind the B-pillar trim near the base of each
B-pillar.
²Side Curtain Airbag- In vehicles equipped
with this option, a side curtain airbag is located on
each inside roof side rail above the headliner, and
extends from the A-pillar to just beyond the C-pillar.
The ACM, both SIACMs, and the EMIC each con-
tain a central processing unit and programming that
allow them to communicate with each other using
the Programmable Communication Interface (PCI)
data bus network. This method of communication is
used by the ACM for control of the airbag indicator
on all models equipped with dual front airbags.
(Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/COMMUNICATION - DESCRIP-
TION).
Hard wired circuitry connects the supplemental
restraint system components to each other through
the electrical system of the vehicle. These hard wired
circuits are integral to several wire harnesses, which
are routed throughout the vehicle and retained by
many different methods. These circuits may be con-
nected to each other, to the vehicle electrical system,
and to the supplemental restraint system compo-
nents through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and insu-
lators. Refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
proper wire and connector repair procedures, further
details on wire harness routing and retention, as well
as pin-out and location views for the various wire
harness connectors, splices and grounds.
OPERATION
ACTIVE RESTRAINTS The primary passenger
restraints in this or any other vehicle are the stan-
dard equipment factory-installed seat belts. Seat
belts are referred to as an active restraint because
the vehicle occupants are required to physically fas-ten and properly adjust these restraints in order to
benefit from them. See the owner's manual in the
vehicle glove box for more information on the fea-
tures, use and operation of all of the factory-installed
active restraints.
PASSIVE RESTRAINTS The passive restraints
system is referred to as a supplemental restraint sys-
tem because they were designed and are intended to
enhance the protection for the vehicle occupants of
the vehicleonlywhen used in conjunction with the
seat belts. They are referred to as passive systems
because the vehicle occupants are not required to do
anything to make them operate; however, the vehicle
occupants must be wearing their seat belts in order
to obtain the maximum safety benefit from the facto-
ry-installed supplemental restraint systems.
The supplemental restraint system electrical cir-
cuits are continuously monitored and controlled by a
microprocessor and software contained within the
Airbag Control Module (ACM) and, on vehicles
equipped with the side curtain airbags, both Side
Impact Airbag Control Modules (SIACM). An airbag
indicator in the ElectroMechanical Instrument Clus-
ter (EMIC) illuminates for about seven seconds as a
bulb test each time the ignition switch is turned to
the On or Start positions. Following the bulb test,
the airbag indicator is turned on or off by the ACM
to indicate the status of the supplemental restraint
system. If the airbag indicator comes on at any time
other than during the bulb test, it indicates that
there is a problem in the supplemental restraint sys-
tem electrical circuits. Such a problem may cause air-
bags not to deploy when required, or to deploy when
not required.
Deployment of the supplemental restraints
depends upon the angle and severity of an impact.
Deployment is not based upon vehicle speed; rather,
deployment is based upon the rate of deceleration as
measured by the forces of gravity (G force) upon the
impact sensors. When an impact is severe enough,
the microprocessor in the ACM or the SIACM signals
the inflator unit of the airbag module to deploy the
airbag. The seat belt tensioner is provided with a
deployment signal by the ACM in conjunction with
the driver airbag. During a frontal vehicle impact,
the knee blockers work in concert with properly fas-
tened and adjusted seat belts to restrain both the
driver and the front seat passenger in the proper
position for an airbag deployment. The knee blockers
also absorb and distribute the crash energy from the
driver and the front seat passenger to the structure
of the instrument panel. The seat belt tensioner
removes the slack from the driver side front seat belt
to provide further assurance that the driver is prop-
erly positioned and restrained for an airbag deploy-
ment.
8O - 4 RESTRAINTSKJ
RESTRAINTS (Continued)

Typically, the vehicle occupants recall more about
the events preceding and following a collision than
they have of an airbag deployment itself. This is
because the airbag deployment and deflation occur so
rapidly. In a typical 48 kilometer-per-hour (30 mile-
per-hour) barrier impact, from the moment of impact
until the airbags are fully inflated takes about 40
milliseconds. Within one to two seconds from the
moment of impact, the airbags are almost entirely
deflated. The times cited for these events are approx-
imations, which apply only to a barrier impact at the
given speed. Actual times will vary somewhat,
depending upon the vehicle speed, impact angle,
severity of the impact, and the type of collision.
When the ACM monitors a problem in any of the
dual front airbag system circuits or components,
including the seat belt tensioner, it stores a fault
code or Diagnostic Trouble Code (DTC) in its memory
circuit and sends an electronic message to the EMIC
to turn on the airbag indicator. When the SIACM
monitors a problem in any of the side curtain airbag
system circuits or component, it stores a fault code or
Diagnostic Trouble Code (DTC) in its memory circuit
and sends an electronic message to the ACM, and the
ACM sends an electronic message to the EMIC to
turn on the airbag indicator. Proper testing of the
airbag system components, the Programmable Com-
munication Interface (PCI) data bus, the data bus
message inputs to and outputs from the EMIC, the
SIACM, or the ACM, as well as the retrieval or era-
sure of a DTC from the ACM, SIACM, or EMIC
requires the use of a DRBIIItscan tool. Refer to the
appropriate diagnostic information.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of all of the factory-installed passive restraints.
WARNING - RESTRAINT SYSTEM
WARNING: DURING AND FOLLOWING ANY SEAT
BELT SERVICE, CAREFULLY INSPECT ALL SEAT
BELTS, BUCKLES, MOUNTING HARDWARE, AND
RETRACTORS FOR PROPER INSTALLATION,
OPERATION, OR DAMAGE. REPLACE ANY BELT
THAT IS CUT, FRAYED, OR TORN. STRAIGHTEN
ANY BELT THAT IS TWISTED. TIGHTEN ANY
LOOSE FASTENERS. REPLACE ANY BELT THAT
HAS A DAMAGED OR INOPERATIVE BUCKLE OR
RETRACTOR. REPLACE ANY BELT THAT HAS A
BENT OR DAMAGED LATCH PLATE OR ANCHOR
PLATE. NEVER ATTEMPT TO REPAIR A SEAT BELT
COMPONENT. ALWAYS REPLACE DAMAGED OR
FAULTY SEAT BELT COMPONENTS WITH THE COR-
RECT, NEW AND UNUSED REPLACEMENT PARTS
LISTED IN THE DAIMLERCHRYSLER MOPAR PARTS
CATALOG.WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSOR, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: AN AIRBAG INFLATOR UNIT MAY CON-
TAIN SODIUM AZIDE AND POTASSIUM NITRATE.
THESE MATERIALS ARE POISONOUS AND
EXTREMELY FLAMMABLE. CONTACT WITH ACID,
WATER, OR HEAVY METALS MAY PRODUCE HARM-
FUL AND IRRITATING GASES (SODIUM HYDROXIDE
IS FORMED IN THE PRESENCE OF MOISTURE) OR
COMBUSTIBLE COMPOUNDS. AN AIRBAG INFLA-
TOR UNIT MAY ALSO CONTAIN A GAS CANISTER
PRESSURIZED TO OVER 2500 PSI. DO NOT
ATTEMPT TO DISMANTLE AN AIRBAG UNIT OR
TAMPER WITH ITS INFLATOR. DO NOT PUNCTURE,
INCINERATE, OR BRING INTO CONTACT WITH
ELECTRICITY. DO NOT STORE AT TEMPERATURES
EXCEEDING 93É C (200É F).
WARNING: WHEN HANDLING A SEAT BELT TEN-
SIONER RETRACTOR, PROPER CARE SHOULD BE
EXERCISED TO KEEP FINGERS OUT FROM UNDER
THE RETRACTOR COVER AND AWAY FROM THE
SEAT BELT WEBBING WHERE IT EXITS FROM THE
RETRACTOR COVER.
WARNING: REPLACE ALL RESTRAINT SYSTEM
COMPONENTS ONLY WITH PARTS SPECIFIED IN
THE DAIMLERCHRYSLER MOPAR PARTS CATA-
LOG. SUBSTITUTE PARTS MAY APPEAR INTER-
CHANGEABLE, BUT INTERNAL DIFFERENCES MAY
RESULT IN INFERIOR OCCUPANT PROTECTION.
KJRESTRAINTS 8O - 5
RESTRAINTS (Continued)

WARNING: THE FASTENERS, SCREWS, AND
BOLTS ORIGINALLY USED FOR THE RESTRAINT
SYSTEM COMPONENTS HAVE SPECIAL COATINGS
AND ARE SPECIFICALLY DESIGNED FOR THE
RESTRAINT SYSTEM. THEY MUST NEVER BE
REPLACED WITH ANY SUBSTITUTES. ANY TIME A
NEW FASTENER IS NEEDED, REPLACE IT WITH
THE CORRECT FASTENERS PROVIDED IN THE
SERVICE PACKAGE OR SPECIFIED IN THE
DAIMLERCHRYSLER MOPAR PARTS CATALOG.
WARNING: WHEN A STEERING COLUMN HAS AN
AIRBAG UNIT ATTACHED, NEVER PLACE THE COL-
UMN ON THE FLOOR OR ANY OTHER SURFACE
WITH THE STEERING WHEEL OR AIRBAG UNIT
FACE DOWN.
DIAGNOSIS AND TESTING - SUPPLEMENTAL
RESTRAINT SYSTEM
Proper diagnosis and testing of the supplemental
restraint system components, the PCI data bus, the
data bus message inputs to and outputs from the
ElectroMechanical Instrument Cluster (EMIC), the
Airbag Control Module (ACM), or the Side Impact
Airbag Control Module (SIACM) as well as the
retrieval or erasure of a Diagnostic Trouble Code
(DTC) from the ACM or SIACM requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
STANDARD PROCEDURE
STANDARD PROCEDURE - HANDLING
NON-DEPLOYED SUPPLEMENTAL RESTRAINTS
At no time should any source of electricity be per-
mitted near the inflator on the back of a non-de-
ployed airbag or seat belt tensioner. When carrying a
non-deployed airbag, the trim cover or airbag cushion
side of the unit should be pointed away from the
body to minimize injury in the event of an accidental
deployment. If the airbag unit is placed on a bench or
any other surface, the trim cover or airbag cushion
side of the unit should be face up to minimize move-
ment in the event of an accidental deployment. When
handling a non-deployed seat belt tensioner, take
proper care to keep fingers out from under the
retractor cover and away from the seat belt webbing
where it exits from the retractor cover. In addition,
the supplemental restraint system should be dis-
armed whenever any steering wheel, steering col-
umn, seat belt tensioner, driver airbag, passenger
airbag, front impact sensor, side curtain airbag, or
instrument panel components require diagnosis or
service. Failure to observe this warning could result
in accidental airbag deployment and possible per-
sonal injury.
All damaged, faulty or non-deployed airbags and
seat belt tensioners which are replaced on vehicles
are to be handled and disposed of properly. If an air-
bag or seat belt tensioner unit is faulty or damaged
and non-deployed, refer to the Hazardous Substance
Control System for proper disposal. Dispose of all
non-deployed and deployed airbags and seat belt ten-
sioners in a manner consistent with state, provincial,
local and federal regulations.
SUPPLEMENTAL RESTRAINT STORAGE
Airbags and seat belt tensioners must be stored in
their original, special container until they are used
for service. Also, they must be stored in a clean, dry
environment; away from sources of extreme heat,
sparks, and high electrical energy. Always place or
store any airbag on a surface with its trim cover or
airbag cushion side facing up, to minimize movement
in case of an accidental deployment.
STANDARD PROCEDURE - SERVICE AFTER A
SUPPLEMENTAL RESTRAINT DEPLOYMENT
Any vehicle which is to be returned to use follow-
ing a supplemental restraint deployment, must have
the deployed restraints replaced. In addition, if the
driver airbag has been deployed, the clockspring
must be replaced. If the passenger airbag is
deployed, the passenger airbag door and both passen-
ger airbag mounting brackets must be replaced. If a
side curtain airbag has been deployed, the complete
8O - 6 RESTRAINTSKJ
RESTRAINTS (Continued)

airbag unit, the headliner, as well as the upper A, B,
and C-pillar trim must be replaced. These compo-
nents are not intended for reuse and will be damaged
or weakened as a result of a supplemental restraint
deployment, which may or may not be obvious during
a visual inspection.
On vehicles with an optional sunroof, the sunroof
drain tubes and hoses must be closely inspected fol-
lowing a side curtain airbag deployment. It is also
critical that the mounting surfaces and/or mounting
brackets for the Airbag Control Module (ACM), Side
Impact Airbag Control Module (SIACM), and front
impact sensors be closely inspected and restored to
their original conditions following any vehicle impact
damage. Because the ACM, SIACM, and each front
impact sensor are used by the supplemental restraint
system to monitor or confirm the direction and sever-
ity of a vehicle impact, improper orientation or inse-
cure fastening of these components may cause
airbags not to deploy when required, or to deploy
when not required. All other vehicle components
should be closely inspected following any other sup-
plemental restraint deployment, but are to be
replaced only as required by the extent of the visible
damage incurred.
AIRBAG SQUIB STATUS
Multistage airbags with multiple initiators (squibs)
must be checked to determine that all squibs were
used during the deployment event. The driver and
passenger airbags in this model are deployed by elec-
trical signals generated by the Airbag Control Mod-
ule (ACM) through the driver or passenger squib 1
and squib 2 circuits to the two initiators in the air-
bag inflators. Typically, both initiators are used andall potentially hazardous chemicals are burned dur-
ing an airbag deployment event. However, it is possi-
ble for only one initiator to be used due to an airbag
system fault; therefore, it is always necessary to con-
firm that both initiators have been used in order to
avoid the improper handling or disposal of poten-
tially live pyrotechnic or hazardous materials. The
following procedure should be performed using a
DRBIIItscan tool to verify the status of both airbag
squibs before either deployed airbag is removed from
the vehicle for disposal.
CAUTION: Deployed front airbags having two initia-
tors (squibs) in the airbag inflator may or may not
have live pyrotechnic material within the inflator. Do
not dispose of these airbags unless you are sure of
complete deployment. Refer to the Hazardous Sub-
stance Control System for proper disposal proce-
dures. Dispose of all non-deployed and deployed
airbags in a manner consistent with state, provin-
cial, local, and federal regulations.
(1) Be certain that the DRBIIItscan tool contains
the latest version of the proper DRBIIItsoftware.
Connect the DRBIIItto the 16-way Data Link Con-
nector (DLC). The DLC is located on the driver side
lower edge of the instrument panel, outboard of the
steering column.
(2) Turn the ignition switch to the On position.
(3) Using the DRBIIIt, read and record the active
(current) Diagnostic Trouble Code (DTC) data.
Using the active DTC information, refer to theAir-
bag Squib Statustable to determine the status of
both driver and/or passenger airbag squibs.
AIRBAG SQUIB STATUS
IF the Active DTC is: Conditions Squib Status
Driver or Passenger Squib 1 openANDthe stored DTC minutes for both
Driver or Passenger squibs are within 15
minutes of each otherBoth Squib 1 and 2
were used.
Driver or Passenger Squib 2 open
Driver or Passenger Squib 1 openANDthe stored DTC minutes for Driver or
Passenger Squib 2 open is GREATER than
the stored DTC minutes for Driver or
Passenger Squib 1 by 15 minutes or moreSquib 1 was used;
Squib 2 is live.
Driver or Passenger Squib 2 open
Driver or Passenger Squib 1 openANDthe stored DTC minutes for Driver or
Passenger Squib 1 open is GREATER than
the stored DTC minutes for Driver or
Passenger Squib 2 by 15 minutes or moreSquib 1 is live; Squib
2 was used.
Driver or Passenger Squib 2 open
Driver or Passenger Squib 1 openANDDriver or Passenger Squib 2 open is
NOT an active codeSquib 1 was used;
Squib 2 is live.
Driver or Passenger Squib 2 openANDDriver or Passenger Squib 1 open is
NOT an active codeSquib 1 is live; Squib
2 was used.
KJRESTRAINTS 8O - 7
RESTRAINTS (Continued)

The ACM housing also has an integral ground lug
with a tapped hole that protrudes from the lower left
rear corner of the unit. This lug provides a case
ground to the ACM when a ground screw is installed
through the left side of the mounting bracket. Two
molded plastic electrical connector receptacles exit
the right side of the ACM housing. The smaller of the
two receptacles contains twelve terminal pins, while
the larger one contains twenty-three. These terminal
pins connect the ACM to the vehicle electrical system
through two dedicated take outs and connectors of
the instrument panel wire harness.
A molded rubber protective cover is installed
loosely over the ACM to protect the unit from con-
densation or coolant leaking from a damaged or
faulty heater-air conditioner unit housing. An inte-
gral flange on the left side of the cover is secured to
the floor panel transmission tunnel with a short
piece of double-faced tape as an assembly aid during
the manufacturing process, but this tape does not
require replacement following service removal.
The impact sensor and safing sensor internal to
the ACM are calibrated for the specific vehicle, and
are only serviced as a unit with the ACM. The ACM
cannot be repaired or adjusted and, if damaged or
faulty, it must be replaced. The ACM cover is avail-
able for separate service replacement.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the front supplemental restraint sys-
tem logic circuits and controls all of the front supple-
mental restraint system components. The ACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used for
control of the airbag indicator in the ElectroMechani-
cal Instrument Cluster (EMIC) and for supplemental
restraint system diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/AIRBAG
INDICATOR - OPERATION).
The ACM microprocessor continuously monitors all
of the front supplemental restraint system electrical
circuits to determine the system readiness. If the
ACM detects a monitored system fault, it sets an
active and stored Diagnostic Trouble Code (DTC) and
sends electronic messages to the EMIC over the PCI
data bus to turn on the airbag indicator. An active
fault only remains for the duration of the fault or in
some cases the duration of the current ignition
switch cycle, while a stored fault causes a DTC to be
stored in memory by the ACM. For some DTCs, if afault does not recur for a number of ignition cycles,
the ACM will automatically erase the stored DTC.
For other internal faults, the stored DTC is latched
forever.
On models equipped with optional side curtain air-
bags, the ACM communicates with both the left and
right Side Impact Airbag Control Modules (SIACM)
over the PCI data bus. The SIACM notifies the ACM
when it has detected a monitored system fault and
stored a DTC in memory for its respective side cur-
tain airbag system, and the ACM sets a DTC and
controls the airbag indicator operation accordingly.
The ACM also monitors a Hall effect-type seat belt
switch located in the buckle of each front seat belt to
determine whether the seatbelts are buckled, and
provides an input to the EMIC over the PCI data bus
to control the seatbelt indicator operation based upon
the status of the driver side front seat belt switch.
The ACM receives battery current through two cir-
cuits; a fused ignition switch output (run) circuit
through a fuse in the Junction Block (JB), and a
fused ignition switch output (run-start) circuit
through a second fuse in the JB. The ACM has a case
ground through a lug on the bottom of the ACM
housing that is secured with a ground screw to the
left side of the ACM mounting bracket. The ACM
also receives a power ground through a ground cir-
cuit and take out of the instrument panel wire har-
ness. This take out has a single eyelet terminal
connector that is secured by a second ground screw
to the left side of the ACM mounting bracket. These
connections allow the ACM to be operational when-
ever the ignition switch is in the Start or On posi-
tions. The ACM also contains an energy-storage
capacitor. When the ignition switch is in the Start or
On positions, this capacitor is continually being
charged with enough electrical energy to deploy the
airbags for up to one second following a battery dis-
connect or failure. The purpose of the capacitor is to
provide backup supplemental restraint system pro-
tection in case there is a loss of battery current sup-
ply to the ACM during an impact.
Two sensors are contained within the ACM, an
electronic impact sensor and a safing sensor. The
ACM also monitors inputs from two remote front
impact sensors located on the back of the right and
left vertical members of the radiator support near
the front of the vehicle. The electronic impact sensors
are accelerometers that sense the rate of vehicle
deceleration, which provides verification of the direc-
tion and severity of an impact. The safing sensor is
an electromechanical sensor within the ACM that
provides an additional logic input to the ACM micro-
processor. The safing sensor is a normally open
switch that is used to verify the need for an airbag
deployment by detecting impact energy of a lesser
8O - 10 RESTRAINTSKJ
AIRBAG CONTROL MODULE (Continued)

screws. A two-wire pigtail harness is routed forward
from the airbag inflator through a trough along the
top of the plastic airbag channel on the roof rail and
down the B-pillar, where it is retained by three rout-
ing clips. The pigtail harness is connected to a take
out and connector of the body wire harness on the
B-pillar, which connects to the respective right or left
Side Impact Airbag Control Module (SIACM) on the
sill panel at the base of the B-pillar.
The side curtain airbag unit cannot be adjusted or
repaired and must be replaced if deployed, faulty, or
in any way damaged. Once a side curtain airbag has
been deployed, the complete airbag unit, the head-
liner, the upper A, B, and C-pillar trim, and all other
visibly damaged components must be replaced.
OPERATION
Each side curtain airbag is deployed individually by
an electrical signal generated by the left or right Side
Impact Airbag Control Module (SIACM) to which it is
connected through left or right curtain airbag line 1 and
line 2 (or squib) circuits. The hybrid-type inflatorassembly for each airbag contains a small canister of
highly compressed helium gas. When the SIACM sends
the proper electrical signal to the airbag inflator, the
electrical energy creates enough heat to ignite chemical
pellets within the inflator. Once ignited, these chemicals
burn rapidly and produce the pressure necessary to rup-
ture a containment disk in the helium gas canister. The
inflator and helium gas canister are sealed and con-
nected to a tubular manifold so that all of the released
gas is directed into the folded curtain airbag cushion,
causing the cushion to inflate.
As the airbag cushion inflates it will drop down
from the roof rail between the edge of the headliner
and the side glass/body pillars to form a curtain-like
cushion to protect the vehicle occupants during a side
impact collision. The front tether keeps the front por-
tion of the bag taut, thus ensuring that the bag will
deploy in the proper position. Following the airbag
deployment, the airbag cushion quickly deflates by
venting the helium gas through the loose weave of
the cushion fabric, and the deflated cushion hangs
down loosely from the roof rail.
Fig. 37 Side Curtain Airbag
1 - INFLATOR
2 - MANIFOLD
3 - CHANNEL
4 - TETHER5 - PIGTAIL WIRE RETAINER (3)
6 - PUSH-IN FASTENER (4)
7 - BRACKET (3)
KJRESTRAINTS 8O - 39
SIDE CURTAIN AIRBAG (Continued)

(10) Reinstall the headliner into the vehicle. (Refer
to 23 - BODY/INTERIOR/HEADLINER - INSTALLA-
TION).
(11) Reinstall the lower trim onto the inside of the
B-pillar. (Refer to 23 - BODY/INTERIOR/B-PILLAR
LOWER TRIM - INSTALLATION).
(12) Do not reconnect the battery negative cable at
this time. The airbag system verification test proce-
dure should be performed following service of any
supplemental restraint system component. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - VERIFICATION TEST).
SIDE IMPACT AIRBAG
CONTROL MODULE
DESCRIPTION
On vehicles equipped with the optional side curtain
airbags, a Side Impact Airbag Control Module
(SIACM) and its mounting bracket are secured with
four screws to the sill panel at the base of each B-pil-
lar behind the lower B-pillar trim (Fig. 43). Con-
cealed within a hollow in the center of the die cast
aluminum SIACM housing is the electronic circuitry
of the SIACM which includes a microprocessor and
an electronic impact sensor. The SIACM housing is
secured to a stamped steel mounting bracket, which
is unique for the right or left side application of this
component. The SIACM should never be removed
from its mounting bracket. The housing also receives
a case ground through this mounting bracket when it
is secured to the vehicle. A molded plastic electrical
connector receptacle that exits the top of the SIACMhousing connects the unit to the vehicle electrical
system through a dedicated take out and connector of
the body wire harness. Both the SIACM housing and
its electrical connection are sealed to protect the
internal electronic circuitry and components against
moisture intrusion.
The impact sensor internal to the SIACM is cali-
brated for the specific vehicle, and is only serviced as
a unit with the SIACM. The SIACM cannot be
repaired or adjusted and, if damaged or faulty, it
must be replaced.
OPERATION
The microprocessor in the Side Impact Airbag Con-
trol Module (SIACM) contains the side curtain airbag
system logic circuits and controls all of the features
of only the side curtain airbag mounted on the same
side of the vehicle as the SIACM. The SIACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used by the
SIACM to communicate with the Airbag Control
Module (ACM) and for supplemental restraints sys-
tem diagnosis and testing through the 16-way data
link connector located on the driver side lower edge
of the instrument panel. The ACM communicates
with both the left and right SIACM over the PCI
data bus.
The SIACM microprocessor continuously monitors
all of the side curtain airbag electrical circuits to
determine the system readiness. If the SIACM
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the ACM over the PCI data
bus. The ACM will respond by sending an electronic
message to the EMIC to turn on the airbag indicator,
and by storing a DTC that will indicate whether the
left or the right SIACM has stored the DTC that ini-
tiated the airbag indicator illumination. An active
fault only remains for the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the SIACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
SIACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
The SIACM receives battery current on a fused
ignition switch output (run-start) circuit through a
fuse in the Junction Block (JB). The SIACM has a
case ground through its mounting bracket and also
receives a power ground through a ground circuit
and take out of the body wire harness. This take out
has a single eyelet terminal connector that is secured
by a ground screw to the front seat front crossmem-
Fig. 43 Side Impact Airbag Control Module
1 - BRACKET (RIGHT SHOWN)
2 - CONNECTOR RECEPTACLE
3 - SIACM
KJRESTRAINTS 8O - 43
SIDE CURTAIN AIRBAG (Continued)

ber beneath the respective right or left front seat.
These connections allow the SIACM to be operational
whenever the ignition switch is in the Start or On
positions. An electronic impact sensor is contained
within the SIACM. The electronic impact sensor is
an accelerometer that senses the rate of vehicle
deceleration, which provides verification of the direc-
tion and severity of an impact. A pre-programmed
decision algorithm in the SIACM microprocessor
determines when the deceleration rate as signaled by
the impact sensor indicates a side impact that is
severe enough to require side curtain airbag protec-
tion. When the programmed conditions are met, the
SIACM sends the proper electrical signals to deploy
the side curtain airbag.
The hard wired inputs and outputs for the SIACM
may be diagnosed and tested using conventional
diagnostic tools and procedures. However, conven-
tional diagnostic methods will not prove conclusive in
the diagnosis of the SIACM, the PCI data bus net-
work, or the electronic message inputs to and outputs
from the SIACM. The most reliable, efficient, and
accurate means to diagnose the SIACM, the PCI data
bus network, and the electronic message inputs to
and outputs from the SIACM requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: THE SIDE IMPACT AIRBAG CONTROL
MODULE CONTAINS THE IMPACT SENSOR, WHICH
ENABLES THE SYSTEM TO DEPLOY THE SIDE
CURTAIN AIRBAGS. NEVER STRIKE OR DROP THE
SIDE IMPACT AIRBAG CONTROL MODULE, AS IT
CAN DAMAGE THE IMPACT SENSOR OR AFFECT
ITS CALIBRATION. IF A SIDE IMPACT AIRBAG CON-
TROL MODULE IS ACCIDENTALLY DROPPED DUR-ING SERVICE, THE MODULE MUST BE SCRAPPED
AND REPLACED WITH A NEW UNIT. FAILURE TO
OBSERVE THIS WARNING COULD RESULT IN ACCI-
DENTAL, INCOMPLETE, OR IMPROPER SIDE CUR-
TAIN AIRBAG DEPLOYMENT AND POSSIBLE
OCCUPANT INJURIES.
(1) Adjust the front seat to its most forward posi-
tion for easiest access to the lower B-pillar trim.
(2) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(3) Remove the lower trim from the inside of the
B-pillar. (Refer to 23 - BODY/INTERIOR/B-PILLAR
LOWER TRIM - REMOVAL).
(4) Disconnect the body wire harness connector for
the Side Impact Airbag Control Module (SIACM)
from the module connector receptacle (Fig. 44).
(5) Disengage the body wire harness retainer from
the tab on the SIACM mounting bracket.
(6) Remove the four screws that secure the SIACM
mounting bracket to the sill panel at the base of the
B-pillar.
(7) Remove the SIACM and its mounting bracket
from the sill panel as a unit.
Fig. 44 Side Impact Airbag Control Module
Remove/Install
1 - B-PILLAR
2 - WIRE HARNESS CONNECTOR
3 - SIACM
4 - SCREW (4)
8O - 44 RESTRAINTSKJ
SIDE IMPACT AIRBAG CONTROL MODULE (Continued)