2002 JEEP LIBERTY Bus switch

proper Diagnostic Procedures manual. The
DRBIIItscan tool can provide confirmation
that the PCI data bus is functional, that all of
the electronic modules are sending and receiv-
ing the proper messages on the PCI data bus,
and that the power lock motors are being sent
the proper hard wired outputs by the relays for
them to perform their power lock system func-
tions.
Following are tests that will help to diagnose the
hard wired components and circuits of the power lock
system. However, these tests may not prove conclu-
sive in the diagnosis of this system. In order to
obtain conclusive testing of the power lock system,
the Programmable Communications Interface (PCI)
data bus network and all of the electronic modules
that provide inputs to, or receive outputs from the
power lock system components must be checked.
The Body Control Module (BCM) will set Diagnos-
tic Trouble Codes (DTC) for the power lock system.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
PRELIMINARY DIAGNOSIS
As a preliminary diagnosis for the power lock sys-
tem, note the system operation while you actuate
both the Lock and Unlock functions with the power
lock switches and with the Remote Keyless Entry
(RKE) transmitter. Then, proceed as follows:
²If the entire power lock system fails to function
with either the power lock switches or the RKE
transmitter, check the fused B(+) fuse in the junction
Block (JB).
²If the power lock system functions with both
power lock switches, but not with the RKE transmit-
ter, proceed to diagnosis of the Remote Keyless Entry
(RKE) system. (Refer to 8 - ELECTRICAL/POWER
LOCKS/KEYLESS ENTRY TRANSMITTER - DIAG-
NOSIS AND TESTING) or (Refer to 8 - ELECTRI-
CAL/POWER LOCKS/REMOTE KEYLESS ENTRY
MODULE - DIAGNOSIS AND TESTING).
²If the power lock system functions with the RKE
transmitter, but not with one or both power lock
switches, proceed to diagnosis of the door lock
switches. (Refer to 8 - ELECTRICAL/POWER
LOCKS/POWER LOCK SWITCH - DIAGNOSIS AND
TESTING).
²If the driver side power lock switch operates
only the driver side front door power lock motor, but
all other power lock motors operate with the passen-
ger side power lock switch or the RKE transmitter,
use a DRBIIItscan tool and the appropriate diagnos-tic information to diagnose the Programmable Com-
munications Interface (PCI) data bus.
²If only one power lock motor fails to operate
with both power lock switches and the RKE trans-
mitter, proceed to diagnosis of the power lock motor.
(Refer to 8 - ELECTRICAL/POWER LOCKS/POWER
LOCK MOTOR - DIAGNOSIS AND TESTING).
DOOR LOCK / UNLOCK
SWITCH
DIAGNOSIS AND TESTING - DOOR LOCK/
UNLOCK SWITCH
(1) Remove the switch to be tested (Refer to 8 -
ELECTRICAL/POWER LOCKS/POWER LOCK
SWITCH - REMOVAL).
(2) Using an ohmmeter, Test switch for resistance
values (Fig. 1).
DOOR LOCK SWITCH TEST
SWITCH
POSITIONPINS RESISTANCE
VALUE
UNACTUATED 1 AND 4 5.0K OHM   10
%
LOCK 1 AND 4 1.4K OHM  10
%
UNLOCK 1 AND 4 426 OHM   10
%
(3) If test results are not obtained as shown in the
test table, replace the switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
Fig. 1 DOOR LOCK/UNLOCK SWITCH
8N - 4 POWER LOCKSKJ
POWER LOCKS (Continued)

(2) Remove the door trim panel (Fig. 2) (Refer to
23 - BODY/DOOR - FRONT/TRIM PANEL - REMOV-
AL).
(3) Disconnect electrical harness connector from
switch.
(4) From behind the door trim panel, gently pry
the switch from the door trim panel (Fig. 3).
INSTALLATION
(1) Press the switch into place.
(2) Connect the electrical harness connector to the
switch.(3) Install the door trim panel (Refer to 23 -
BODY/DOOR - FRONT/TRIM PANEL - INSTALLA-
TION).
(4) Connect the battery negative cable.
DOOR LOCK MOTOR
DESCRIPTION
The lock mechanisms are actuated by a reversible
electric motor mounted within each door and tailgate.
The power lock motors are integral to the door latch
units.
The power lock motors cannot be adjusted or
repaired and, if faulty or damaged, the door latch
unit must be replaced.
OPERATION
The door lock motors are controlled by relays. A
positive and negative battery connection to the two
motor terminals will cause the motor to move in one
direction. Reversing the current will cause the motor
to move in the opposite direction.
DIAGNOSIS AND TESTING - DOOR LOCK
MOTOR
The most reliable, efficient, and accurate means to
diagnose the power lock system requires the use of a
DRBIIItscan tool and the proper Diagnostic Proce-
dures manual. The DRBIIItscan tool can provide
confirmation that the PCI data bus is functional, that
all of the electronic modules are sending and receiv-
ing the proper messages on the PCI data bus, and
that the power lock motors are being sent the proper
hard wired outputs by the door modules for them to
perform their power lock system functions.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
FLIP-UP GLASS RELEASE
SWITCH
DIAGNOSIS AND TESTING - FLIP-UP GLASS
RELEASE SWITCH
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the tailgate trim panel (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
TRIM PANEL - REMOVAL).
(3) Disconnect the wire harness connector.
Fig. 2 DOOR LOCK SWITCH
1 - DOOR TRIM PANEL
2 - DOOR LOCK SWITCH
3 - POWER MIRROR SWITCH
Fig. 3 DOOR LOCK/MIRROR SWITCH
1 - DOOR TRIM PANEL
2 - DOOR LOCK SWITCH
3 - POWER MIRROR SWITCH
KJPOWER LOCKS 8N - 5
DOOR LOCK / UNLOCK SWITCH (Continued)

Press and hold the transmitter UNLOCK button
for four to ten seconds. While pressing the UNLOCK
button in, press the LOCK button. Release both but-
tons.
This will toggle between Driver door first and
Unlock all doors function.
STANDARD PROCEDURE - RKE TRANSMITTER
PROGRAMING
New Remote Keyless Entry (RKE) transmitters can
be programed using the DRBIIItscan tool and the
proper Diagnostic Procedures manual. The DRBIIIt
scan tool can provide confirmation that the PCI data
bus is functional, and that all of the electronic mod-
ules are sending and receiving the proper messages
on the PCI data bus.
The following procedure can be used as long as one
functioning transmitter is available:
(1) Using the original transmitter, press the
UNLOCK button for 4 to 10 seconds.
(2) Without releasing the UNLOCK button, press
the PANIC button (within the 4 to 10 second inter-
val).
(3) Release both buttons.
(4) Press LOCK and UNLOCK simultaneously on
the original transmitter.
(5) Release both buttons.
(6) Press any button on the ORIGINAL transmit-
ter. A chime tone from the instrument cluster will
confirm the programming of the ORIGINAL trans-
mitter.
(7) On NEW transmitter, press LOCK and
UNLOCK simultaneously.
(8) Release both buttons.
(9) Press any button on the NEW transmitter. A
chime tone from the instrument cluster will confirm
the programming of the NEW transmitter.
(10) Up to four transmitters can be programed for
one vehicle.
SPECIFICATIONS - REMOTE KEYLESS ENTRY
TRANSMITTER
RANGE
Normal operation range is up to a distance of 3 to
7 meters (10 to 23 ft.) of the vehicle. Range may be
better or worse depending on the environment
around the vehicle.
TAILGATE CYLINDER LOCK
SWITCH
DESCRIPTION
The tailgate cylinder lock switch is integral to the
key lock cylinder inside the tailgate. The tailgate cyl-
inder lock switch is a normally-open momentary
switch that is hard wired directly to the Body Con-
trol Module (BCM), and closes a path to ground
through an internal resistor when the lock cylinder is
rotated to the unlock or lock position.
The tailgate cylinder lock switch cannot be
adjusted or repaired.
OPERATION
The tailgate cylinder lock switch is actuated when
the key is inserted in the lock cylinder and turned to
the unlock or lock position. The tailgate cylinder lock
switch closes a path to ground through an internal
resistor for the Body Control Module (BCM) when
the tailgate key lock cylinder is in the lock or unlock
position, and opens the ground path when the lock
cylinder is in the neutral position. The BCM reads
the switch status, then sends the proper switch sta-
tus messages to other electronic modules over the
Programmable Communications Interface (PCI) data
bus network. The tailgate cylinder lock switch unlock
status message is used by the BCM as an input for
Vehicle Theft Security System (VTSS) operation and
to tell the BCM to lock or unlock the tailgate. There
is no mechanical linkage between the tailgate key
cylinder and the latches.
DIAGNOSIS AND TESTING - TAILGATE
CYLINDER LOCK SWITCH
(1) Disconnect and isolate the battery negative
cable.
(2) Remove tailgate trim panel (Refer to 23 -
BODY/DECKLID/HATCH/LIFTGATE/TAILGATE/
TRIM PANEL - REMOVAL).
(3) Disconnect tailgate cylinder lock switch har-
ness connector.
(4) Using a ohmmeter, test for resistances as
shown in the Tailgate Cylinder Lock Switch Table.
KJPOWER LOCKS 8N - 9
REMOTE KEYLESS ENTRY TRANSMITTER (Continued)

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)

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)

magnitude than that of the electronic impact sensors,
and must be closed in order for the airbags/seat belt
tensioner to deploy. A pre-programmed decision algo-
rithm in the ACM microprocessor determines when
the deceleration rate as signaled by the impact sen-
sors and the safing sensor indicate an impact that is
severe enough to require front supplemental
restraint system protection and, based upon the sta-
tus of the seatbelt switch inputs and the severity of
the monitored impact, determines what combination
of driver seat belt tensioner and/or front airbag
deployment is required for each front seating posi-
tion. When the programmed conditions are met, the
ACM sends the proper electrical signals to deploy the
driver seat belt tensioner and/or the multistage dual
front airbags at the programmed force levels.
The hard wired inputs and outputs for the ACM
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 ACM, the PCI data bus network,
or the electronic message inputs to and outputs from
the ACM. The most reliable, efficient, and accurate
means to diagnose the ACM, the PCI data bus net-
work, and the electronic message inputs to and out-
puts from the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
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 AIRBAG CONTROL MODULE CON-
TAINS THE IMPACT SENSOR, WHICH ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE AIRBAG CONTROL MODULE, AS IT CAN DAM-
AGE THE IMPACT SENSOR OR AFFECT ITS CALI-
BRATION. IF AN AIRBAG CONTROL MODULE ISACCIDENTALLY DROPPED DURING SERVICE, THE
MODULE MUST BE SCRAPPED AND REPLACED
WITH A NEW UNIT. FAILURE TO OBSERVE THIS
WARNING COULD RESULT IN ACCIDENTAL,
INCOMPLETE, OR IMPROPER FRONT SUPPLEMEN-
TAL RESTRAINT DEPLOYMENT AND POSSIBLE
OCCUPANT INJURIES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Remove the center console from the top of the
floor panel transmission tunnel. (Refer to 23 - BODY/
INTERIOR/FLOOR CONSOLE - REMOVAL).
(3) From the left side of the floor panel transmis-
sion tunnel, remove the Airbag Control Module
(ACM) cover from the ACM (Fig. 7). The cover flange
is secured to the silencer pad on the floor panel
transmission tunnel with double-faced tape.
(4) Remove the ground screw that secures the
ground lug on the left rear corner of the ACM hous-
ing to the ACM bracket on the floor panel transmis-
sion tunnel.
Fig. 7 ACM Cover Remove/Install
1 - FLANGE
2 - COVER
3 - TAPE
4 - SCREW
5 - BRACKET
6 - AIRBAG CONTROL MODULE
7 - FLOOR PANEL TRANSMISSION TUNNEL
KJRESTRAINTS 8O - 11
AIRBAG CONTROL MODULE (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)