2002 JEEP GRAND CHEROKEE Bus

PASSENGER SIDE FRONT AND REAR WINDOWS
INOPERATIVE
If the driver side front and rear power windows
operate, but the passenger side front and rear do not,
use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to check the PCI data bus for proper
operation.
ONE WINDOW INOPERATIVE
The window glass and regulator mechanism must
be free to slide up and down for the power window
motor to function properly. If the window glass and
regulator is not free to move up and down, the motor
will overload and trip the integral circuit breaker. To
determine if the window glass and regulator are free,
disconnect the regulator plate from the glass. Then
slide the window up and down by hand.
There is an alternate method to check if the win-
dow glass and regulator mechanism is free. Position
the glass between the up and down stops. Then,
shake the glass in the door. Check that the glass can
be moved slightly from side to side, front to rear, and
up and down. Then check that the glass is not bound
tight in the tracks.
If the window glass and regulator mechanism is
free, refer toDoor Modulein Electrical, Power Win-
dows. If the glass is not free, inspect the window
glass mounting and operating hardware for damage
or improperly installed components. Refer toBodyto
check for proper installation or damage of the win-
dow glass mounting and operating hardware.
DOOR MODULE
NOTE: The following tests may not prove conclu-
sive in the diagnosis of this component. The most
reliable, efficient, and accurate means to diagnose
this component requires the use of a DRB scan tool
and the proper Diagnostic Procedures manual.
If the problem being diagnosed is a rear door win-
dow that does not operate from the rear door switch,
but does operate from the master switch on the
driver side front door, (Refer to 8 - ELECTRICAL/
POWER WINDOWS/POWER WINDOW SWITCH -
DIAGNOSIS AND TESTING). If the problem is a
passenger side front or rear window that operates
from the switch on that door, but does not operate
from the master switch on the driver side front door,
use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to diagnose the circuitry of both door
modules and the PCI data bus. For complete circuit
diagrams, refer to the appropriate wiring informa-
tion. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
details of wire harness routing and retention, connec-tor pin-out information and location views for the
various wire harness connectors, splices and grounds.
(1) Disconnect and isolate the battery negative
cable. Remove the trim panel from the front door, but
do not disconnect the door wire harness connectors
from the door module. Go to Step 2.
(2) Check the 15-way door wire harness connector
for the door module to see that it is fully seated in
the door module connector receptacle. If OK, go to
Step 3. If not OK, properly connect the 15-way door
wire harness connector for the door module to the
door module connector receptacle.
(3) Disconnect the 15-way door wire harness con-
nector from the door module connector receptacle.
Check for continuity between the ground circuit cav-
ity of the 15-way door wire harness connector for the
door module and a good ground. There should be con-
tinuity. If OK, go to Step 4. If not OK, repair the
open ground circuit to ground as required.
(4) Connect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
15-way door wire harness connector for the door
module. If OK, go to Step 5. If not OK, repair the
open fused B(+) circuit to the fuse in the Power Dis-
tribution Center (PDC) as required.
(5) If the inoperative window is on a front door, go
to Step 6. If the inoperative window is on a rear door
go to Step 9.
(6) Disconnect and isolate the battery negative
cable. Disconnect the door wire harness connector
from the inoperative power window motor wire har-
ness connector. Check for continuity between the
front window driver up circuit cavity of the 15-way
door wire harness connector for the door module and
a good ground. Repeat the check for the front window
driver down circuit. In each case there should be no
continuity. If OK, go to Step 7. If not OK, repair the
shorted front window driver up or down circuit as
required.
(7) Check for continuity between the front window
driver up circuit cavities of the 15-way door wire har-
ness connector for the door module and the door wire
harness connector for the power window motor.
Repeat the check for the front window driver down
circuit. In each case there should be continuity. If
OK, go to Step 8. If not OK, repair the open front
window driver up or down circuit as required.
(8) Reconnect the 15-way door wire harness con-
nector back into the door module connector recepta-
cle. Connect the battery negative cable. Connect the
probes of a reversible DC digital voltmeter to the
door wire harness connector for the power window
motor. Observe the voltmeter while actuating the
switch for that window in the up and down direc-
tions. There should be battery voltage for as long as
the switch is held in both the up and down positions,
WJPOWER WINDOWS 8N - 35
POWER WINDOWS (Continued)

and no voltage in the neutral position. If OK,(Refer
to 8 - ELECTRICAL/POWER WINDOWS/WINDOW
MOTOR - DIAGNOSIS AND TESTING). If not OK,
replace the faulty door module.
(9) Check the rear door power window switch con-
tinuity. (Refer to 8 - ELECTRICAL/POWER WIN-
DOWS/POWER WINDOW SWITCH - DIAGNOSIS
AND TESTING). If OK, go to Step 10. If not OK,
replace the faulty rear door power window switch.
(10) Disconnect and isolate the battery negative
cable. Reconnect the door wire harness connector to
the rear door power window switch. Disconnect the
door wire harness connector from the inoperative
power window motor wire harness connector. Check
for continuity between the rear window driver up cir-
cuit cavity of the 15-way door wire harness connector
for the door module and a good ground. Repeat the
check for the rear window driver down circuit. In
each case there should be no continuity. If OK, go to
Step 11. If not OK, repair the shorted rear window
driver up or down circuit as required.
(11) Check for continuity between the rear window
driver up circuit cavities of the 15-way door wire har-
ness connector for the door module and the power
window motor wire harness connector. Repeat the
check for the rear window driver down circuit. In
each case there should be continuity. If OK, go to
Step 12. If not OK, repair the open rear window
driver up or down circuit as required.
NOTE: The door module feeds battery current to
both terminals of the rear door power window
motors when the power window lockout switch is in
the Unlock position, until the master window switch
on the driver side front door is actuated. The door
module feeds ground to both terminals of the rear
door power window motor when the power window
lockout switch is in the Lock position, until the
master window switch on the driver side front door
is actuated.
(12) Reconnect the 15-way door wire harness con-
nector for the door module to the door module con-
nector receptacle. Connect the battery negative cable.
Check for battery voltage at each cavity in the door
wire harness connector for the power window motor.
Each cavity should have battery voltage when the
power window switch is in the neutral position. Each
cavity should also have battery voltage in one other
switch position, either up or down, and zero volts
with the switch in the opposite position. If OK, (Refer
to 8 - ELECTRICAL/POWER WINDOWS/WINDOW
MOTOR - DIAGNOSIS AND TESTING). If not OK,
replace the faulty door module.POWER WINDOW SWITCH
DESCRIPTION
The power window motors are controlled by a two-
way momentary switch mounted on the trim panel of
each passenger door, and four two-way momentary
switches on the driver side front door trim panel. The
driver side front door trim panel also has a two-posi-
tion power window lockout switch. Each power win-
dow switch, except the lockout switch, is illuminated
by a Light-Emitting Diode (LED) that is integral to
the switch paddle.
The front door power window switches and the
power window lockout switch are integral to the
Driver Door Module (DDM) and Passenger Door
Module (PDM). The front door power window
switches and their lamps cannot be adjusted or
repaired and, if faulty or damaged, the entire DDM
or PDM unit must be replaced. The rear door power
window switches and their lamps cannot be adjusted
or repaired but, if faulty or damaged, only the
affected rear door power window switch must be
replaced. (Refer to 8 - ELECTRICAL/ELECTRONIC
CONTROL MODULES/DRIVER DOOR MODULE -
REMOVAL).
OPERATION
The front door power window switches provide an
up or down (or lock and unlock signal in the case of
the lockout switch) to the door module circuitry. The
Driver Door Module (DDM) circuitry controls the out-
put to the driver side front and rear door power win-
dow motors, and supplies electrical current as
required for the stand-alone operation of the driver
side rear door power window switch. The Passenger
Door Module (PDM) circuitry controls the output to
the passenger side front and rear door power window
motors, and supplies electrical current as required
for the stand-alone operation of the passenger side
rear door power window switch.
When a DDM-integrated master power window
switch for a passenger side window is actuated, or
when the power window lockout switch is actuated to
disable the passenger door power windows, the DDM
circuitry sends a message to the PDM over the Pro-
grammable Communications Interface (PCI) data bus
to control the output to that power window motor(s).
The power window switch for the driver side front
door power window has two detent positions in the
Down direction. The first detent provides normal
power window down operation. If this switch is
depressed to the second detent, the Auto Down cir-
cuitry of the DDM is activated. The Auto-Down cir-
cuitry will automatically move the driver side front
door window to its fully lowered position, even if the
power window switch is released. The Auto-Down
8N - 36 POWER WINDOWSWJ
POWER WINDOWS (Continued)

²Passenger Airbag- The passenger airbag is
located on the instrument panel, beneath the instru-
ment panel top pad and 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.
²Side Impact Sensor- Two side impact sensors
are used on vehicles with the optional side curtain
airbags, one left side and one right side. One sensor
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 and the EMIC each contain a central
processing unit and programming that allow them to
communicate with each other using the Programma-
ble 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 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/
COMMUNICATION - DESCRIPTION).
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 standard equipment factory-in-
stalled seat belts. Seat belts are referred to as an
active restraint because the vehicle occupants are
required to physically fasten 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 features, use and operation of all
of the factory-installed active restraints.PASSIVE RESTRAINTS
The passive restraints system is referred to as a
supplemental restraint system 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 factory-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). An airbag indicator in
the ElectroMechanical Instrument Cluster (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 prob-
lem in the supplemental restraint system electrical
circuits. Such a problem may cause airbags 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 signals the inflator
unit of the airbag module to deploy the airbag. Dur-
ing a frontal vehicle impact, the knee blockers work
in concert with properly fastened and adjusted seat
belts to restrain both the driver and the front seat
passenger in the proper position for an airbag deploy-
ment. 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.
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,
8O - 4 RESTRAINTSWJ
RESTRAINTS (Continued)

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
airbag system circuits or components, 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. Proper
testing of the airbag system components, the Pro-
grammable Communication Interface (PCI) data bus,
the data bus message inputs to and outputs from the
EMIC or the ACM, as well as the retrieval or erasure
of a DTC from the ACM or EMIC requires the use of
a DRBIIItscan tool. Refer to the appropriate diag-
nostic 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, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
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: 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.
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) or the
Airbag Control Module (ACM), as well as the
retrieval or erasure of a Diagnostic Trouble Code
(DTC) from the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
WJRESTRAINTS 8O - 5
RESTRAINTS (Continued)

(4) Check to be certain that nobody is in the vehi-
cle, then reconnect the battery negative cable.
(5) Using the DRBIIIt, read and record the active
(current) Diagnostic Trouble Code (DTC) data.
(6) Next, use the DRBIIItto read and record any
stored (historical) DTC data.
(7) If any DTC is found in Step 5 or Step 6, refer
to the appropriate diagnostic information.
(8) Use the DRBIIItto erase the stored DTC data.
If any problems remain, the stored DTC data will not
erase. Refer to the appropriate diagnostic informa-
tion to diagnose any stored DTC that will not erase.
If the stored DTC information is successfully erased,
go to Step 9.
(9) Turn the ignition switch to the Off position for
about fifteen seconds, and then back to the On posi-
tion. Observe the airbag indicator in the instrument
cluster. It should light for six to eight seconds, and
then go out. This indicates that the supplemental
restraint system is functioning normally and that the
repairs are complete. If the airbag indicator fails to
light, or lights and stays on, there is still an active
supplemental restraint system fault or malfunction.
Refer to the appropriate diagnostic information to
diagnose the problem.
AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is also some-
times referred to as the Occupant Restraint Control-
ler (ORC) (Fig. 6). The ACM is concealed underneath
the center floor console, where it is secured by four
screws to a stamped steel mounting bracket welded
onto the top of the floor panel transmission tunnel
just forward of the park brake mechanism in the pas-
senger compartment of the vehicle.
Concealed within a hollow in the center of the die
cast aluminum ACM housing is the electronic cir-
cuitry of the ACM which includes a microprocessor,
an electronic impact sensor, an electronic safing sen-
sor, and an energy storage capacitor. A stamped
metal cover plate is secured to the bottom of the
ACM housing with four screws to enclose and protect
the internal electronic circuitry and components. A
printed label on the top of the ACM housing provides
a visual verification of the proper orientation of the
unit, and should always be pointed toward the front
of the vehicle.
Two molded plastic electrical connector receptacles
exit the forward side of the ACM housing. These two
receptacles connect the ACM to the vehicle electrical
system through a dedicated take out and connector of
the instrument panel wire harness, and a dedicated
take out and connector of the airbag overlay wire
harness. For vehicles equipped with the optional side
curtain airbags, both ACM connector receptacles are
black in color and the ACM contains a second bi-di-
rectional safing sensor for the side airbags. For vehi-
cles not equipped with the optional side curtain
airbags, the ACM connector receptacles are both
gray.
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.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the supplemental restraint system
logic circuits and controls all of the supplemental
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/ELECTRONIC CONTROL MOD-
ULES/COMMUNICATION - OPERATION).
Fig. 6 Airbag Control Module
1 - AIRBAG CONTROL MODULE
2 - ORIENTATION ARROW
3 - LABEL
4 - MOUNTING HOLES (4)
5 - CONNECTOR RECEPTACLE (2)
WJRESTRAINTS 8O - 9
RESTRAINTS (Continued)

The ACM microprocessor continuously monitors all
of the supplemental restraint system electrical cir-
cuits 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 a fault
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 for-
ever.
The ACM receives battery current through two cir-
cuits, on a fused ignition switch output (run) circuit
through a fuse in the Junction Block (JB), and on a
fused ignition switch output (start-run) circuit
through a second fuse in the JB. The ACM is
grounded through a ground circuit and take out of
the instrument panel floor wire harness. This take
out has a single eyelet terminal connector secured by
a nut to a ground stud located behind the ACM
mount on the floor panel transmission tunnel. 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 brackets on the inboard
sides 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 provide
verification of the direction and severity of an
impact. On models equipped with optional side cur-
tain airbags, the ACM also monitors inputs from two
remote side impact sensors located near the base of
both the left and right inner B-pillars to control the
deployment of the side curtain airbag units.
The safing sensor is an electronic accelerometer
sensor within the ACM that provides an additional
logic input to the ACM microprocessor. The safingsensor is used to verify the need for an airbag
deployment by detecting impact energy of a lesser
magnitude than that of the primary electronic impact
sensors, and must exceed a safing threshold in order
for the airbags to deploy. The ACM also monitors a
Hall effect-type seat belt switch located in the buckle
of each front seat belt to determine whether the seat-
belts are buckled, and provides an input to the EMIC
over the PCI data bus to control the seatbelt indica-
tor operation based upon the status of the driver side
front seat belt switch. Vehicles with the optional side
curtain airbags feature a second safing sensor within
the ACM to provide confirmation to the ACM of side
impact forces. This second safing sensor is a bi-direc-
tional unit that detects impact forces from either side
of the vehicle.
Pre-programmed decision algorithms in the ACM
microprocessor determine when the deceleration rate
as signaled by the impact sensors and the safing sen-
sors indicate an impact that is severe enough to
require supplemental restraint system protection.
The ACM also determines the level of front airbag
deployment force required for each front seating posi-
tion based upon the status of the two seat belt switch
inputs and the severity of the monitored impact.
When the programmed conditions are met, the ACM
sends the proper electrical signals to deploy the mul-
tistage dual front airbags at the programmed force
levels, and to deploy either side curtain airbag.
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
Two different Airbag Control Modules (ACM) are
available for this vehicle. For vehicles equipped with
the optional side curtain airbags, both ACM connec-
tor receptacles are black in color and the ACM con-
tains a second bi-directional safing sensor for the
side airbags. For vehicles not equipped with the
optional side curtain airbags, the ACM connector
receptacles are gray.
8O - 10 RESTRAINTSWJ
AIRBAG CONTROL MODULE (Continued)

CONTROL/CENTRAL TIMER MODULE -
DESCRIPTION).
²Combination Flasher (Refer to 8 - ELECTRI-
CAL/LAMPS/LIGHTING - EXTERIOR/COMBINA-
TION FLASHER - DESCRIPTION).
²Door Ajar Switch (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/DOOR AJAR
SWITCH - DESCRIPTION - DOOR AJAR SWITCH).
²Driver Cylinder Lock Switch (Refer to 8 - ELEC-
TRICAL/POWER LOCKS/DOOR CYLINDER LOCK/
UNLOCK SWITCH - DESCRIPTION).
²Hood Ajar Switch(Refer to 8 - ELECTRICAL/VE-
HICLE THEFT SECURITY/HOOD AJAR SWITCH -
DESCRIPTION).
²Horn Relay (Refer to 8 - ELECTRICAL/HORN/
HORN RELAY - DESCRIPTION).
²Liftgate Ajar Switch (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/DOOR AJAR
SWITCH - DESCRIPTION - LIFTGATE AJAR
SWITCH).
²Liftgate Flip-Up Glass Ajar Switch(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - INTERIOR/
DOOR AJAR SWITCH - DESCRIPTION - LIFTGATE
FLIP-UP GLASS AJAR SWITCH).
²Low Beam Headlamp Relay
²VTSS Indicator (Refer to 8 - ELECTRICAL/VE-
HICLE THEFT SECURITY/VTSS INDICATOR -
DESCRIPTION).
Certain functions and features of the VTSS rely
upon resources shared with or controlled by other
modules in the vehicle over the Programmable Com-
munications Interface (PCI) data bus network. The
other modules that may affect VTSS operation are:
²Driver Door Module (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/DOOR MOD-
ULE - DESCRIPTION).
²Passenger Door Module (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/DOOR
MODULE - DESCRIPTION).
DESCRIPTION - SENTRY KEY IMMOBILIZER
SYSTEM
Vehicles equipped with the Sentry Key Immobilizer
System (SKIS) can be identified by the presence of
an amber SKIS indicator in the instrument cluster
that will illuminate for about three seconds each
time the ignition switch is turned to the On position,
or by a gray molded rubber cap on the head of the
ignition key. Models not equipped with SKIS still
have a SKIS indicator in the cluster, but it will not
illuminate. Also, models not equipped with the SKIS
have a black molded rubber cap on the head of the
ignition key.
The SKIS includes the following major components,
which are described in further detail elsewhere in
this service manual:²Powertrain Control Module
²Sentry Key Immobilizer Module
²Sentry Key Transponder
²SKIS Indicator
Except for the Sentry Key transponders, which rely
upon Radio Frequency (RF) communication, hard
wired circuitry connects the SKIS components to the
electrical system of the vehicle.Refer to the appropri-
ate wiring information.
OPERATION
OPERATION - VEHICLE THEFT SECURITY
SYSTEM
The Vehicle Theft Security System (VTSS) is
divided into two basic subsystems: Vehicle Theft
Alarm (VTA) and Sentry Key Immobilizer System
(SKIS). The following are paragraphs that briefly
describe the operation of each of those two sub-
systems.
A Body Control Module (BCM) is used to control
and integrate many of the functions and features
included in the Vehicle Theft Security System
(VTSS). In the VTSS, the BCM receives inputs indi-
cating the status of the door ajar switches, the driver
cylinder lock switch, the ignition switch, the liftgate
ajar switches, the liftgate flip-up glass ajar switch,
the power lock switches and, in vehicles so equipped,
the hood ajar switch. The programming in the BCM
allows it to process the information from all of these
inputs and send control outputs to energize or de-en-
ergize the combination flasher, the horn relay (except
vehicles with the premium version of the VTA), and
the VTSS indicator. In addition, in vehicles built for
certain markets where premium versions of the VTA
is required, the BCM also exchanges messages with
the Intrusion Transceiver Module (ITM) over the Pro-
grammable Communications Interface (PCI) data
buss network to provide the features found in this
version of the VTA. The control of these inputs and
outputs are what constitute all of the features of the
VTSS. Following is information on the operation of
each of the VTSS features.
ENABLING
The BCM must have the VTSS function enabled in
order for the VTSS to perform as designed. The logic
in the BCM keeps its VTSS function dormant until it
is enabled using a DRBIIItscan tool. Refer to the
appropriate diagnostic information.
PRE-ARMING
The VTA has a pre-arming sequence. Pre-arming
occurs when a door, the tailgate, or the flip-up glass
is open when the vehicle is locked using a power lock
8Q - 2 VEHICLE THEFT SECURITYWJ
VEHICLE THEFT SECURITY (Continued)

switch, or when the ªLockº button on the Remote
Keyless Entry (RKE) transmitter is depressed. The
powerlock switch will not initiate the pre-arming
sequence if the key is in the ignition switch. When
the VTA is pre-armed, the arming sequence is
delayed until all of the doors, the tailgate and the
flip-up glass are closed.
ARMING
Passive arming of the VTSS occurs when the vehi-
cle is exited with the key removed from the ignition
switch, the headlamps are turned off, and the doors
are locked while they are open using the power lock
switch. The power lock switch will not function if the
key is in the ignition switch or the headlamps are
turned on with the driver side front door open. The
VTSS will not arm if the driver side front door is
locked using the key in the lock cylinder or using the
mechanical lock button. Active arming of the VTSS
occurs when the ªLockº button on the Remote Key-
less Entry (RKE) transmitter is depressed to lock the
vehicle, even if the doors and/or the liftgate are open
when the RKE transmitter Lock button is depressed.
However, the VTSS arming will not be complete until
all of the doors, the liftgate and the liftgate flip-up
glass are closed. On vehicles equipped with the hood
ajar switch, VTSS arming will complete if the hood is
open, but the underhood area will not be protected
unless the hood is closed when the VTSS is armed.
Following successful passive or active VTSS arm-
ing, the VTSS indicator on the top of the instrument
panel will flash rapidly for about sixteen seconds
after the illuminated entry system times out. This
indicates that VTSS arming is in progress. Once the
sixteen second arming function is successfully com-
pleted, the indicator will flash at a slower rate, indi-
cating that the VTSS is armed.
DISARMING
Passive disarming of the VTSS occurs when the
vehicle is unlocked using the key to unlock the driver
side front door. Active disarming of the VTSS occurs
when the vehicle is unlocked by depressing the
ªUnlockº button of the Remote Keyless Entry (RKE)
transmitter. Once the alarm has been activated,
either disarming method will also deactivate the
alarm. Depressing the ªPanicº button on the RKE
transmitter will also disarm the VTSS, but the horn
will continue to pulse and the exterior lamps will
continue to flash for about three minutes as part of
the Panic feature function. The Panic feature is over-
ridden if the ªPanicº button is depressed a second
time, or if a vehicle speed of about 24 kilometers-per-
hour (15 miles-per-hour) is attained.POWER-UP MODE
When the armed VTSS senses that the battery has
been disconnected and reconnected, it enters its pow-
er-up mode. In the power-up mode the alarm system
remains armed following a battery failure or discon-
nect. If the VTSS was armed prior to a battery dis-
connect or failure, the technician or vehicle operator
will have to actively or passively disarm the alarm
system after the battery is reconnected. The pow-
er-up mode will also apply if the battery goes dead
while the system is armed, and battery jump-starting
is then attempted. The VTSS will be armed until it is
actively or passively disarmed. If the VTSS is in the
disarmed mode prior to a battery disconnect or fail-
ure, it will remain disarmed after the battery is
reconnected or replaced, or if jump-starting is
attempted.
ALARM
The VTA alarm output varies by the version of the
VTA with which the vehicle is equipped. In all cases,
the alarm provides both visual and audible outputs;
however, the time intervals of these outputs vary by
the requirements of the market for which the vehicle
is manufactured. In all cases, the visual output will
be a flashing of the exterior lamps. For vehicles
equipped with North American or the base version of
the VTA, the audible output will be the pulsing of the
horn. For vehicles with the premium version of the
VTA, the audible output will be the cycling of the
siren. The inputs that will trigger the alarm include
the door ajar switch, the flip-up glass ajar switch,
and in vehicles built for certain markets where they
are required, the hood ajar switch and the Intrusion
Transceiver Module (ITM).
TAMPER ALERT
The VTSS tamper alert feature will sound the horn
(or the alarm siren for the premium version) three
times upon VTA disarming, if the alarm was trig-
gered and has since timed-out (about eighteen min-
utes). This feature alerts the vehicle operator that
the VTA alarm was activated while the vehicle was
unattended.
INTRUSION ALARM
The Intrusion Alarm is an exclusive feature of the
premium version of the VTA, which is only available
in certain markets, where it is required. When the
VTA is armed, a motion sensor in the Intrusion
Transceiver Module (ITM) monitors the interior of
the vehicle for movement. If motion is detected, the
ITM sends a message to the BCM over the PCI bus
to invoke the visual alarm feature, and sends a mes-
sage to the alarm siren over a dedicated serial bus to
invoke the audible alarm feature. The motion detec-
WJVEHICLE THEFT SECURITY 8Q - 3
VEHICLE THEFT SECURITY (Continued)