2002 JEEP GRAND CHEROKEE electrical circuit

POWER SEAT SYSTEM
TABLE OF CONTENTS
page page
POWER SEAT SYSTEM
DESCRIPTION
DESCRIPTION........................18
DESCRIPTION - MEMORY SYSTEM.......19
OPERATION
OPERATION - POWER SEAT SYSTEM.....20
OPERATION - MEMORY SYSTEM.........20
DIAGNOSIS AND TESTING
DIAGNOSIS & TESTING - POWER SEAT
SYSTEM............................20
DIAGNOSIS & TESTING - MEMORY
SYSTEM............................20
DRIVER SEAT SWITCH
DESCRIPTION.........................21
OPERATION...........................21
DIAGNOSIS AND TESTING - DRIVER SEAT
SWITCH............................22
REMOVAL.............................23
INSTALLATION.........................23
LUMBAR CONTROL SWITCH
DESCRIPTION.........................24
OPERATION...........................24
DIAGNOSIS AND TESTING - POWER LUMBAR
SWITCH............................24
REMOVAL.............................24
INSTALLATION.........................25
LUMBAR MOTOR
DESCRIPTION.........................25OPERATION...........................26
DIAGNOSIS AND TESTING - POWER LUMBAR
ADJUSTER..........................26
MEMORY SET SWITCH
DESCRIPTION.........................26
OPERATION...........................26
DIAGNOSIS AND TESTING - MEMORY
SWITCH............................27
REMOVAL.............................27
INSTALLATION.........................27
PASSENGER SEAT SWITCH
DESCRIPTION.........................27
OPERATION...........................28
DIAGNOSIS AND TESTING - PASSENGER
SEAT SWITCH........................28
REMOVAL.............................29
INSTALLATION.........................29
RECLINER MOTOR
DESCRIPTION.........................30
OPERATION...........................30
DIAGNOSIS AND TESTING - RECLINER
MOTOR .............................30
POWER SEAT TRACK
DESCRIPTION.........................31
OPERATION...........................32
DIAGNOSIS AND TESTING - POWER SEAT
TRACK.............................32
POWER SEAT SYSTEM
DESCRIPTION
DESCRIPTION
Driver and passenger power front seats are an
available factory-installed option for this vehicle. The
power seat system option allows the driver and front
seat passenger to electrically adjust their seating
positions for optimum control and comfort using the
power seat switches located on the outboard seat
cushion side shield of each front seat. The power seat
system receives battery current through a fuse in the
Power Distribution Center (PDC) and a circuit
breaker in the junction block so that the power seats
remain operational, regardless of the ignition switch
position.Four power seat options are offered on this vehicle,
depending upon the model. They are as follows:
²Six-way power drivers seat with manual
passenger seat- This power seat package is an
option on Laredo models equipped with cloth-
trimmed seats and includes a six-way adjustable
driver seat track with manual seat back recliners.
²Six-way power driver and passenger seat-
This power seat package is an option on Laredo mod-
els equipped with cloth or leather-trimmed seats and
includes six-way adjustable seat tracks with manual
seat back recliners. Heated Seats are available on
leather-trimmed seats.
²Ten-way power drivers seat with Memory
and Six-way power passenger seat- This power
seat package is standard on Limited models. This
option includes a six-way adjustable seat track with
power seat back recliners and power lumbar supports
for the driver and six-way only for the passenger.
8N - 18 POWER SEAT SYSTEMWJ

(2) Check for battery voltage at the power seat cir-
cuit breaker in the junction block. If OK, go to Step
3. If not OK, repair the open fused B(+) circuit to the
fuse in the Power Distribution Center as required.
(3) Remove the outboard seat cushion side shield
from the seat. Disconnect the seat wire harness con-
nector from the power seat switch connector recepta-
cle. Check for battery voltage at the fused B(+)
circuit cavity of the power seat wire harness connec-
tor for the power seat switch. If OK, go to Step 4. If
not OK, repair the open fused B(+) circuit to the
power seat circuit breaker in the junction block as
required.(4) Check for continuity between the ground cir-
cuit cavity of the power seat wire harness connector
for the power seat switch and a good ground. There
should be continuity. If OK, go to Step 5. If not OK,
repair the open ground circuit to ground as required.
(5) Test the power seat switch. Refer toPower
Seat Switch Diagnosis and Testingin this group.
If the switch tests OK, test the circuits of the power
seat wire harness between the power seat recliner
adjuster motor and the power seat switch for shorts
or opens. If the circuits check OK, replace the faulty
power seat recliner unit. If the circuits are not OK,
repair the power seat wire harness as required.
POWER SEAT TRACK
DESCRIPTION
Both the six-way and the ten-way power seat
options include a single electrically operated power
seat track unit located under each front bucket seat
(Fig. 21). The power seat track unit replaces the
standard equipment manual seat tracks. The lower
half of the power seat track is secured at the front
with two screws to the floor panel seat cross member,
and at the rear with two screws to the floor panel.
Four nuts secure the bottom of the seat cushion
frame to four studs on the upper half of the power
seat track unit.
The power seat track unit cannot be repaired, and is
serviced only as a complete unit. If any component in
this unit is faulty or damaged, the entire power seat
track unit must be replaced. Refer toBucket Seat
Track Adjuster
in Body for the service procedure.
Fig. 20 Power Seat Recliner and Track - Typical
1 - SEAT BACK FRAME
2 - SEAT CUSHION PAD
3 - POWER RECLINER
4 - SEAT CUSHION FRAME
5 - SHIELD
6 - POWER SEAT TRACK ADJUSTER
Fig. 21 Power Seat Track - Typical
1 - DRIVE UNITS
2 - LOWER SEAT TRACKS
3 - POWER SEAT MOTORS
4 - SEAT CUSHION FRAME
WJPOWER SEAT SYSTEM 8N - 31
RECLINER MOTOR (Continued)

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)

event will be automatically cancelled and the window
movement will be stopped if the DDM circuitry
detects a second input from the driver side front door
power window switch, in either direction.
Each power window switch, except the lockout
switch, is illuminated by a Light-Emitting Diode
(LED) when the ignition switch is turned to the On
position. However, when the lockout switch is placed
in the Lock position, the LED for the locked-out front
and rear passenger door power window switches is
turned off.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the power window switches.
DIAGNOSIS AND TESTING - POWER WINDOW
SWITCH
The diagnosis found here applies only to the rear
door power window switches. If the problem being
diagnosed is an inoperative power window switch
illumination lamp, but the power window switch
operates as designed, replace the faulty rear door
power window switch(verify the power lockout
switch is not actuated). For complete circuit dia-
grams, 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.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the power window switch from the
rear door trim panel. (Refer to 8 - ELECTRICAL/
POWER WINDOWS/POWER WINDOW SWITCH -
REMOVAL).
(3) Check the rear door power window switch con-
tinuity as shown in the Rear Door Power Window
Switch Continuity chart (Fig. 1). If OK, (Refer to 8 -
ELECTRICAL/POWER WINDOWS/WINDOW
MOTOR - DIAGNOSIS AND TESTING). If not OK,
replace the faulty rear door power window switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the trim panel from the rear door.
(Refer to 23 - BODY/DOORS - REAR/TRIM PANEL -
REMOVAL) for the procedures.
(3) Using a trim stick or another suitable wide
flat-bladed tool, gently pry the sides of the switch
receptacle on the back of the rear door trim panel
away from the perimeter of the power window switch
to release the switch from the receptacle (Fig. 2).
(4) Remove the power window switch from the
rear door trim panel switch receptacle.
Fig. 1 Rear Door Power Window Switch Continuity
SWITCH POSITION CONTINUITY BETWEEN
LED 3 AND 6
OFF 1 AND 2
OFF 4 AND 5
FORWARD 1 AND 2
FORWARD 5 AND 6
REARWARD 2 AND 6
REARWARD 4 AND 5
Fig. 2 Rear Door Power Window Switch Remove/
Install
1 - REAR DOOR TRIM PANEL
2 - TRIM PANEL RECEPTACLE
3 - POWER WINDOW SWITCH
WJPOWER WINDOWS 8N - 37
POWER WINDOW SWITCH (Continued)

INSTALLATION
(1) Position the power window switch to the rear
door trim panel switch receptacle.
(2) Press firmly and evenly on the back of the
power window switch until it snaps into rear door
trim panel switch receptacle.
(3) Install the trim panel onto the rear door. (Refer
to 23 - BODY/DOORS - REAR/TRIM PANEL -
INSTALLATION) for the procedures.
(4) Reconnect the battery negative cable.
WINDOW MOTOR
DESCRIPTION
Power operated front and rear door windows are
standard equipment on this model. Each door has a
permanent magnet reversible electric motor with an
integral right angle gearbox mechanism that oper-
ates the window regulator. In addition, each power
window motor is equipped with an integral self-reset-
ting circuit breaker to protect the motor from over-
loads.
The power window motor gearbox housing is
secured to the window regulator drum housing with
screws. The window regulators used in all four doors
are single vertical post cable-and-drum type. A
molded plastic slider guided by the post is driven by
the regulator cables. The slider raises and lowers the
window glass through a steel lift plate attachment.
Front and rear glass channels within each door guide
and stabilize each end of the glass.
The power window motor and gearbox assembly
cannot be repaired and, if faulty or damaged, the
entire power window motor and gearbox unit must be
replaced. The window regulators are available for
service. (Refer to 23 - BODY/DOOR - FRONT/WIN-
DOW REGULATOR - REMOVAL) or (Refer to 23 -
BODY/DOORS - REAR/WINDOW REGULATOR -
REMOVAL) for the regulator service procedures.
OPERATION
A positive and negative battery connection to the
two motor terminals will cause the power window
motor to rotate in one direction. Reversing the cur-
rent through these same two connections will cause
the motor to rotate in the opposite direction.
When the power window motor operates, it rotates
the regulator cable drum through its gearbox. The
window regulator cable drum is connected through
two cables to the plastic slider on the vertical post.
As the cable drum rotates, it lets cable out on one
side of the drum, and takes cable in on the other side
of the drum. The changes in cable length move the
slider up or down the vertical post, raising or lower-
ing the window glass.If the window regulator or window glass bind,
encounter obstructions, or reach their travel limits it
overloads the power window motor. The overloading
condition causes the power window motor self-reset-
ting circuit breaker to open, which stops the motor
from running.
DIAGNOSIS AND TESTING - WINDOW MOTOR
Before you proceed with this diagnosis, confirm
proper switch operation. (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/DRIVER
DOOR MODULE - OPERATION) or (Refer to 8 -
ELECTRICAL/POWER WINDOWS/POWER WIN-
DOW SWITCH - OPERATION). 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) Remove the trim panel from the door with the
inoperative power window. (Refer to 23 - BODY/
DOOR - FRONT/TRIM PANEL - REMOVAL) or
(Refer to 23 - BODY/DOORS - REAR/TRIM PANEL -
REMOVAL) for the procedures.
(2) Disconnect the door wire harness connector
from the power window motor wire harness connec-
tor. Apply battery current to one cavity of the power
window motor wire harness connector, and apply
ground to the other cavity of the connector. The
power window motor should operate in one direction.
Remember, if the window is in the full up or full
down position, the motor will not operate in that
direction by design. If OK, go to Step 3. If not OK,
replace the faulty power window motor.
(3) Reverse the battery and ground connections to
the two cavities of the power window motor wire har-
ness connector. The power window motor should now
operate in the other direction. Remember, if the win-
dow is in the full up or full down position, the motor
will not operate in that direction by design. If OK, go
to Step 4. If not OK, replace the faulty power window
motor.
(4) If the power window motor operates in both
directions, check the operation of the window glass
and regulator mechanism through its complete up
and down travel. There should be no binding or stick-
ing of the window glass or regulator mechanism
through the entire travel range. If not OK, (Refer to
23 - BODY/DOOR - FRONT/WINDOW REGULATOR
- REMOVAL) or (Refer to 23 - BODY/DOORS -
REAR/WINDOW REGULATOR - REMOVAL) to
check for proper installation or damage of the win-
dow glass mounting and operating hardware.
8N - 38 POWER WINDOWSWJ
POWER WINDOW SWITCH (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)

(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)