2002 JEEP LIBERTY junction block

(4) Using an ohmmeter, check for continuity
between the pins of the wire harness connector while
pulling on the tailgate handle.
(5) If no continuity is found, replace the tailgate
handle assembly (Refer to 23 - BODY/DECKLID/
HATCH/LIFTGATE/TAILGATE/EXTERIOR HAN-
DLE - REMOVAL).
DOOR LOCK RELAY
DESCRIPTION
The power door lock system uses the following
relays for the front and rear passenger doors only:
²Driver door unlock relay
²Door lock relay
²Passenger Doors unlock relay
The tailgate uses outputs from the Body Control
Module (BCM).
The relays are electromechanical devices that
switch battery current to the door lock circuit when
the Body Control Module (BCM) grounds the relay
coil. These relays are located in the Junction Block
(JB). For complete circuit diagrams, refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
The relays are a International Standards Organi-
zation (ISO) micro-relay. Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions. The ISO micro-relay terminal functions
are the same as a conventional ISO relay. However,
the ISO micro-relay terminal pattern (or footprint) is
different, the current capacity is lower, and the phys-
ical dimensions are smaller than those of the conven-
tional ISO relay.
The relay cannot be repaired or adjusted and, if
faulty or damaged, it must be replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor and three (two fixed and one movable) elec-
trical contacts. The movable (common feed) relay con-
tact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.When the electromagnetic coil is de-energized,
spring pressure returns the movable contact to the
normally closed position. The resistor is connected in
parallel with the electromagnetic coil in the relay,
and helps to dissipate voltage spikes that are pro-
duced when the coil is de-energized.
DIAGNOSIS AND TESTING - DOOR LOCK
RELAY
The power lock relays (Fig. 4) are located in the
Junction Block (JB) under the instrument panel. For
complete circuit diagrams, 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.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Remove suspected faulty relay from the (JB).
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   8 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If not OK, replace the faulty relay.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Reach up under instrument panel and remove
the relay from Junction Block (JB).
8N - 6 POWER LOCKSKJ
FLIP-UP GLASS RELEASE SWITCH (Continued)

INSTALLATION
(1) Position the horn relay in the proper receptacle
in the Junction Block (JB).
(2) Push down firmly on the relay until the termi-
nals are fully seated.
(3) Connect the battery negative cable.
REMOTE KEYLESS ENTRY
MODULE
DESCRIPTION
When an RKE lock message is sent to the Body
Control Module (BCM), the BCM actuates the doors
and the tailgate lock, the interior lighting is turned
off, the horn chirps (if this feature is enabled), the
exterior lamps flash (if this feature is enabled) and, if
the vehicle is so equipped, the Vehicle Theft Security
System (VTSS) is armed. When an RKE unlock mes-
sage is sent to the BCM, the BCM actuates the
driver side front door (or all doors and the tailgate if
this feature is enabled) unlock, the interior lighting
is turned on and, if the vehicle is so equipped, the
VTSS is disarmed.When an RKE panic message is sent to the BCM,
the BCM actuates the driver side front door (or all
doors and the tailgate if this feature is enabled)
unlock, the interior lighting is turned on and, if the
vehicle is so equipped, the VTSS is disarmed. The
panic message will also cause the exterior lamps
(including the headlights) to flash, and the horn to
pulse for about three minutes, or until a second panic
message is sent to the BCM. A vehicle speed of about
25.7 kilometers-per-hour (15 miles-per-hour) will also
cancel the panic event.
Refer to the owner's manual for more information
on the features, use and operation of the RKE sys-
tem.
OPERATION
Whenever the vehicle battery power is interrupted,
the Remote Keyless Module (RKE) Module will retain
all vehicle access codes in its memory. When replac-
ing or adding a key fob transmitter (maximum of 4) a
DRB IIItscan tool is required to program the RKE
Module to accept the new Vehicle Access Code if a
customer owned transmitter is not available.
If a functioning transmitter is available, (Refer to 8
- ELECTRICAL/POWER LOCKS/KEYLESS ENTRY
TRANSMITTER - STANDARD PROCEDURE)
DIAGNOSIS AND TESTING - REMOTE KEYLESS
ENTRY MODULE
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 har-
ness connectors, splices and grounds. Refer to the
proper Body Diagnostic Procedures Manual for test-
ing the Remote Keyless Entry system using a DRB
IIItscan tool.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the Junction Block (JB) (Refer to 8 -
ELECTRICAL/POWER DISTRIBUTION/JUNCTION
BLOCK - REMOVAL).
(3) Remove Remote Keyless Entry module from
Body Control Module (Fig. 5).
INSTALLATION
(1) Install Remote Keyless Entry module to Body
Control Module.
(2) Install Junction Block (JB) (Refer to 8 - ELEC-
TRICAL/POWER DISTRIBUTION/JUNCTION
BLOCK - INSTALLATION).
(3) Connect the battery negative cable.
Fig. 4 Power Lock Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJPOWER LOCKS 8N - 7
DOOR LOCK RELAY (Continued)

REMOTE KEYLESS ENTRY
TRANSMITTER
DIAGNOSIS AND TESTING - REMOTE KEYLESS
ENTRY TRANSMITTER
The most reliable, efficient, and accurate means to
diagnose the remote keyless entry transmitter
requires the use of a 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.
STANDARD PROCEDURE
STANDARD PROCEDURE - RKE TRANSMITTER
BATTERIES
The Remote Keyless Entry (RKE) transmitter case
snaps open and shut for battery access. To replace
the RKE transmitter batteries:(1) Using a thin coin, gently pry at the notch in
the center seam of the RKE transmitter case halves
near the key ring until the two halves unsnap.
(2) Lift the back half of the transmitter case off of
the RKE transmitter.
(3) Remove the two batteries from the RKE trans-
mitter.
(4) Replace the two batteries with new Panasonic
2016, or equivalent. Be certain that the batteries are
installed with their polarity correctly oriented.
(5) Align the two RKE transmitter case halves
with each other, and squeeze them firmly and evenly
together until they snap back into place.
STANDARD PROCEDURE - RKE TRANSMITTER
CUSTOMER PREFERENCES
AUTOMATIC (ROLLING) LOCKS
The rolling locks feature can be toggled ON/OFF
by using the DRB IIItonly.
HORN CHIRP DISABLING / ENABLING
The horn chirp can be toggled using a DRB IIItor
by using the Remote Keyless Entry (RKE) transmit-
ter.
To DISABLE (cancel) the horn chirp feature, press
and hold the transmitter LOCK button for four to ten
seconds. While pressing the LOCK button in, press
the UNLOCK button. Release both buttons.
To ENABLE the horn chirp feature, repeat the
above procedure.
OPTICAL CHIRP (FLASH) DISABLING / ENABLING
The optical chirp can be toggled using a DRB IIIt
or by using the Remote Keyless Entry (RKE) trans-
mitter.
To DISABLE (cancel) the optical chirp feature,
press and hold the transmitter LOCK button for four
to ten seconds. While pressing the LOCK button in,
press the TAILGATE RELEASE button. Release both
buttons.
To ENABLE the optical chirp feature, repeat the
above procedure.
TAIL GATE RELEASE DELAY
Press the UNLOCK button for four to ten seconds.
While pressing the UNLOCK button, press the TAIL
GATE RELEASE button. Release both buttons.
This will toggle between PRESS AND HOLD and
PRESS (no delay).
UNLOCK SEQUENCE
The unlock sequence can be toggled using a DRB
IIItor by using the Remote Keyless Entry (RKE)
transmitter.
Fig. 5 RKE Module Remove/Install
1 - SCREW (4)
2 - RKE MODULE
3 - BODY CONTROL MODULE
4 - JUNCTION BLOCK
8N - 8 POWER LOCKSKJ
REMOTE KEYLESS ENTRY MODULE (Continued)

POWER MIRRORS
TABLE OF CONTENTS
page page
POWER MIRRORS
DESCRIPTION.........................11
OPERATION...........................11
DIAGNOSIS AND TESTING - POWER
MIRRORS...........................11
POWER MIRROR SWITCH
DIAGNOSIS AND TESTING - POWER MIRROR
SWITCH............................12REMOVAL.............................13
INSTALLATION.........................13
SIDEVIEW MIRROR
REMOVAL.............................13
POWER MIRRORS
DESCRIPTION
The available power operated sideview mirrors
allow the driver to adjust both outside mirrors elec-
trically from the drivers seat by operating a switch
on the driver side front door trim panel (Fig. 1).
OPERATION
The power mirrors receive ignition current through
a fuse in the junction block, and will only operate
when the ignition switch is in the Run position.
DIAGNOSIS AND TESTING - POWER MIRRORS
WIRING VOLTAGE TEST
The following wiring test determines whether or
not voltage is continuous through the body harness
to switch.
(1) Remove the power mirror switch (Refer to 8 -
ELECTRICAL/POWER MIRRORS/POWER MIRROR
SWITCH - REMOVAL).
(2) Disconnect wire connector from back of power
mirror switch.
(3) Switch ignition to the RUN position.
(4) Connect the clip end of a 12 volt test light to
Pin 5 in the harness connector at the mirror switch.
Touch the test light probe to Pin 3.
If the test light illuminates, the wiring circuit
between the battery and switch is OK.
If the lamp does not illuminate, first check fuse 25
in the Junction Block (JB). If fuse 25 is OK, then
check for a broken wire.
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.
POWER MIRROR MOTOR TEST
If the power mirror switch is receiving proper cur-
rent and ground and mirrors do not operate, proceed
with power mirror motor test. Refer to the appropri-
ate 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 connec-
tors, splices and grounds.
Fig. 1 POWER MIRROR SWITCH
1 - DOOR TRIM PANEL
2 - DOOR LOCK SWITCH
3 - POWER MIRROR SWITCH
KJPOWER MIRRORS 8N - 11

POWER SEATS
TABLE OF CONTENTS
page page
POWER SEATS
DESCRIPTION.........................14
OPERATION...........................15
DIAGNOSIS AND TESTING - POWER SEATS . . 15
SEAT TRACK
DESCRIPTION.........................15
OPERATION...........................15
DIAGNOSIS AND TESTING - SEAT TRACK....16
REMOVAL.............................16
INSTALLATION.........................16
LEFT POWER SEAT SWITCH
DESCRIPTION.........................16OPERATION...........................17
DIAGNOSIS AND TESTING - LEFT POWER
SEAT SWITCH........................17
REMOVAL.............................18
INSTALLATION.........................18
RIGHT POWER SEAT SWITCH
DESCRIPTION.........................19
OPERATION...........................19
DIAGNOSIS AND TESTING - RIGHT POWER
SEAT SWITCH........................19
REMOVAL.............................20
INSTALLATION.........................20
POWER SEATS
DESCRIPTION
Individually controlled, electrically powered front
seats are available as factory-installed equipment on
this model. Vehicles with this option can be visually
identified by the two separate power seat switches,
mounted on each of the front seat cushion side
shields (Fig. 1). The power seat system option allows
the front seating positions to be electrically adjustedfor optimum vehicle control and comfort. The power
seat cushion can be adjusted forward, rearward, front
up, front down, rear up, or rear down. The power
seat system for this vehicle includes the following
major components, which are described in further
detail later in this section:
²Power Seat Switches- Two power seat
switches are used per vehicle, one for the driver and
one for the front seat passenger. Refer to the left and
right power seat switch information later in this sec-
tion.
²Power Seat Tracks- Two power seat tracks
are used per vehicle, one for the driver and one for
the front seat passenger seats. Refer to the power
seat track information later in this section.
²Circuit Breaker- An automatic resetting cir-
cuit breaker (# 1) is located in the Junction Block
and is used to protect the power seat system from
current overload.
Hard wired circuitry connects the power seat sys-
tem 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 differ-
ent methods. These circuits may be connected to each
other, to the vehicle electrical system and to the
power seat system components through the use of a
combination of soldered splices, splice block connec-
tors and many different types of wire harness termi-
nal connectors and insulators. Refer to theWiring
section of this manual for more information. The wir-
ing 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 har-
ness connectors, splices and grounds.
Fig. 1 KJ Heated/Power Seat
8N - 14 POWER SEATSKJ

OPERATION
The power seat system receives battery current
through a fuse in the Power Distribution Center
(PDC) and a circuit breaker in the Junction Block,
regardless of the ignition switch position.
When a power seat switch control knob or knobs
are actuated, a battery feed and a ground path are
applied through the switch contacts to the appropri-
ate power seat track adjuster motor. The selected
adjuster motor operates to move the seat track
through its drive unit in the selected direction until
the switch is released, or until the travel limit of the
seat track is reached. When the switch is moved in
the opposite direction, the battery feed and ground
path to the motor are reversed through the switch
contacts. This causes the adjuster motor to run in the
opposite direction.
Refer to the owner's manual in the vehicle glove
box for more information on the features, use and
operation of the power seat system.
DIAGNOSIS AND TESTING - POWER SEATS
Before any testing of the power seat system is
attempted, the battery should be fully-charged and
all wire harness connections and pins cleaned and
tightened to ensure proper continuity and grounds.
Refer to the appropriate wiring information. The wir-
ing information includes wiring diagrams, proper
wire and connector repair procedures, further details
on wire harness routing and retention, as well as
pin-out and joint connector location views for the var-
ious wire harness connectors, splices and grounds.
(1) If all power seats are inoperative, check the
automatic resetting circuit breaker in the Junction
Block. (Refer to 8 - ELECTRICAL/POWER DISTRI-
BUTION/CIRCUIT BREAKER - DIAGNOSIS AND
TESTING).
(2) With the dome lamp on, apply the power seat
switch in the direction of the failure.
(3) If the dome lamp dims, the seat or the power
seat track may be jammed. Check under and behind
the seat for binding or obstructions.
(4) If the dome lamp does not dim, proceed with
testing of the individual power seat system compo-
nents and circuits.
SEAT TRACK
DESCRIPTION
The six-way power seat option includes a power
seat track assembly located under each front seat
(Fig. 2). The power seat track assembly replaces the
standard manually operated seat tracks. The lower
half of the power seat track is secured at the frontwith two bolts to the floor panel seat cross member,
and at the rear with one bolt and one nut to the floor
panel. Four bolts secure the bottom of the seat cush-
ion frame to the upper half of the power seat track
unit.
The power seat track assembly cannot be repaired,
and is serviced only as a complete assembly. If any
component in this assembly is faulty or damaged, the
entire power seat track must be replaced.
OPERATION
The power seat track unit includes three reversible
electric motors that are secured to the upper half of
the track unit. Each motor moves the seat adjuster
through a combination of worm-drive gearboxes and
screw-type drive units. Each of the three driver side
power seat track motors also has a position potenti-
ometer integral to the motor assembly, which elec-
tronically monitors the motor position.
The front and rear of the seat are operated by two
separate vertical adjustment motors. These motors
can be operated independently of each other, tilting
the entire seat assembly forward or rearward; or,
they can be operated in unison by selecting the
proper power seat switch functions, which will raise
or lower the entire seat assembly. The third motor is
the horizontal adjustment motor, which moves the
seat track in the forward and rearward directions.
Fig. 2 Power Seat Track - Typical
1 - POWER SEAT ADJUSTER AND MOTORS
2 - SEAT CUSHION FRAME
3 - POWER SEAT TRACK ASSEMBLY
KJPOWER SEATS 8N - 15
POWER SEATS (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)