exj 8m, JEEP Manuals, Electronic Service Manual (jeep cherokee xj do 2000)
[ Pobierz całość w formacie PDF ]
XJ
PASSIVE RESTRAINT SYSTEMS
8M - 1
PASSIVE RESTRAINT SYSTEMS
TABLE OF CONTENTS
page
page
DESCRIPTION AND OPERATION
DIAGNOSIS AND TESTING
SERVICE PROCEDURES
REMOVAL AND INSTALLATION
DRIVER SIDE AIRBAG MODULE TRIM
ADJUSTMENTS
SPECIAL TOOLS
DESCRIPTION AND OPERATION
²
Airbag indicator lamp
²
Clockspring
AIRBAG SYSTEM
²
Driver
and
passenger
side
airbag
modules
(including the airbag inflators)
²
Driver and passenger side knee blockers
DESCRIPTION
A dual front airbag system is standard factory-in-
stalled safety equipment on this model. The primary
passenger restraints in this vehicle are the standard
equipment factory-installed seat belts, which require
active use by the vehicle occupants. The airbag sys-
tem is a supplemental passive restraint that was
designed and is intended to enhance the protection
for the front seat occupants of the vehicle
only
when
used in conjunction with the seat belts. See the own-
er’s manual in the vehicle glove box for more infor-
mation on the features, use and operation of all of
the factory-installed passenger restraints, including
the airbag system.
Wire harness and connections.
This group provides complete service information
for the ACM, both airbag modules, and the clock-
spring. Complete service information for the other
airbag system components can be located as follows:
²
²
Refer to
Instrument Cluster
in the proper sec-
tion of Group 8E - Instrument Panel Systems for
complete service information for the airbag indicator
lamp.
²
Refer to
Knee Blocker
in the Removal and
Installation section of Group 8E - Instrument Panel
Systems
for
complete
service
information
on
the
driver side knee blocker.
²
Refer to
Glove Box
in the Removal and Instal-
lation section of Group 8E - Instrument Panel Sys-
tems
NOTE: This group covers both Left-Hand Drive
(LHD) and Right-Hand Drive (RHD) versions of this
model. Whenever required and feasible, the RHD
versions of affected vehicle components have been
constructed as mirror-image of the LHD versions.
While most of the illustrations used in this group
represent only the LHD version, the diagnostic and
service procedures outlined can generally be
applied to either version. Exceptions to this rule
have been clearly identified as LHD or RHD, if a
special illustration or procedure is required.
for
complete
service
information
on
the
passenger side knee blocker.
²
Refer to
Airbag System
in the Contents of
Group 8W - Wiring Diagrams for complete service
information and circuit diagrams for the airbag sys-
tem wiring components.
See the proper Diagnostic Procedures manual to
test or diagnose a problem with any component of
the airbag system.
OPERATION
The airbag system electrical circuits are continu-
ously monitored and controlled by a microprocessor
and software contained within the Airbag Control
The dual front airbag system consists of the follow-
ing components:
²
Airbag Control Module (ACM)
 8M - 2
PASSIVE RESTRAINT SYSTEMS
XJ
DESCRIPTION AND OPERATION (Continued)
Module (ACM). The ACM also contains an impact
sensor and a safing sensor, which are monitored by
the ACM to determine when an impact occurs that is
severe enough to require airbag system protection.
When a frontal impact is severe enough, the ACM
signals the inflator units of both airbag modules to
deploy the airbags.
An airbag indicator lamp in the instrument cluster
lights 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 indica-
tor lamp is turned on or off by the ACM to indicate
the status of the airbag system. If the airbag indica-
tor lamp comes on at any time other than during the
bulb test, it indicates that there is a problem in the
airbag system circuits. Such a problem may cause
the airbags not to deploy when required, or to deploy
when not required.
The driver side airbag module includes an inflat-
able airbag and an inflator unit behind a trim cover
in the hub area of the steering wheel. The passenger
side airbag module includes a second inflatable air-
bag and an inflator unit behind an airbag door in the
instrument panel above the glove box.
During a frontal vehicle impact, the knee blockers
work in concert with properly adjusted seat belts to
restrain the driver and front seat passenger in the
proper position for an airbag deployment. The knee
blockers also work to absorb and distribute the crash
energy from the driver and front seat passenger to
the structure of the instrument panel. The driver
side knee blocker is a stamped metal reinforcement
located behind the instrument panel steering column
opening cover. The passenger side knee blocker is
integral to the glove box door.
Following
WITH ACID, WATER, OR HEAVY METALS MAY PRO-
DUCE HARMFUL AND IRRITATING GASES (SODIUM
HYDROXIDE IS FORMED IN THE PRESENCE OF
MOISTURE) OR COMBUSTIBLE COMPOUNDS. THE
PASSENGER AIRBAG MODULE CONTAINS ARGON
GAS PRESSURIZED TO OVER 2500 PSI. DO NOT
ATTEMPT TO DISMANTLE AN AIRBAG MODULE OR
TAMPER WITH ITS INFLATOR. DO NOT PUNCTURE,
INCINERATE, OR BRING INTO CONTACT WITH
ELECTRICITY. DO NOT STORE AT TEMPERATURES
EXCEEDING 93° C (200° F).
²
REPLACE AIRBAG SYSTEM COMPONENTS
ONLY WITH PARTS SPECIFIED IN THE CHRYSLER
MOPAR PARTS CATALOG. SUBSTITUTE PARTS
MAY APPEAR INTERCHANGEABLE, BUT INTERNAL
DIFFERENCES MAY RESULT IN INFERIOR OCCU-
PANT PROTECTION.
²
THE FASTENERS, SCREWS, AND BOLTS ORIG-
INALLY USED FOR THE AIRBAG SYSTEM COMPO-
NENTS HAVE SPECIAL COATINGS AND ARE
SPECIFICALLY DESIGNED FOR THE AIRBAG SYS-
TEM. THEY MUST NEVER BE REPLACED WITH ANY
SUBSTITUTES. ANY TIME A NEW FASTENER IS
NEEDED, REPLACE IT WITH THE CORRECT FAS-
TENERS PROVIDED IN THE SERVICE PACKAGE OR
SPECIFIED IN THE CHRYSLER MOPAR PARTS CAT-
ALOG.
²
WHEN A STEERING COLUMN HAS AN AIRBAG
MODULE ATTACHED, NEVER PLACE THE COLUMN
ON THE FLOOR OR ANY OTHER SURFACE WITH
THE STEERING WHEEL OR AIRBAG MODULE FACE
DOWN.
DRIVER SIDE AIRBAG MODULE
are
general
descriptions
of
the
major
DESCRIPTION
The driver side airbag module protective trim cover
is the most visible part of the driver side airbag sys-
tem. The driver side airbag module is mounted
directly to the steering wheel. Located under the air-
bag module trim cover are the horn switch, the
folded airbag cushion, and the airbag cushion sup-
porting components. The resistive membrane-type
horn switch is secured with heat stakes to the inside
surface of the airbag module trim cover, between the
trim cover and the folded airbag cushion.
The driver side airbag module cannot be repaired,
and must be replaced if deployed or in any way dam-
aged. The driver side airbag module trim cover and
the horn switch are available as a unit for service
replacement.
components in the airbag system.
WARNING:
²
THE AIRBAG SYSTEM IS A SENSITIVE, COM-
PLEX ELECTROMECHANICAL UNIT. BEFORE
ATTEMPTING TO DIAGNOSE OR SERVICE ANY AIR-
BAG SYSTEM OR RELATED STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENTS YOU MUST FIRST DISCONNECT
AND ISOLATE THE BATTERY NEGATIVE (GROUND)
CABLE. THEN WAIT TWO MINUTES FOR THE SYS-
TEM CAPACITOR TO DISCHARGE BEFORE FUR-
THER SYSTEM SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO DO THIS COULD RESULT IN ACCIDENTAL AIR-
BAG
DEPLOYMENT
AND
POSSIBLE
PERSONAL
INJURY.
²
OPERATION
The driver side airbag module includes a stamped
metal housing to which the cushion and an inflator
THE DRIVER SIDE AIRBAG MODULE INFLATOR
ASSEMBLY CONTAINS SODIUM AZIDE AND POTAS-
SIUM NITRATE. THESE MATERIALS ARE POISON-
OUS
AND
EXTREMELY
FLAMMABLE.
CONTACT
 XJ
PASSIVE RESTRAINT SYSTEMS
8M - 3
DESCRIPTION AND OPERATION (Continued)
unit are attached and sealed. The conventional pyro-
technic-type inflator assembly is mounted to studs on
the back of the airbag module housing. The inflator
seals the hole in the airbag cushion so it can dis-
charge the gas it produces directly into the cushion
when supplied with the proper electrical signal. Fol-
lowing an airbag deployment, the airbag cushion
quickly deflates by venting this gas towards the
instrument panel through the porous fabric material
used on the steering wheel side of the airbag cushion.
The protective trim cover is fitted to the front of
the airbag module and forms a decorative cover in
the center of the steering wheel. The inside of the
trim cover has locking blocks molded into it that
engage a lip on the airbag module metal housing.
Two stamped metal retainers then fit over the infla-
tor mounting studs on the back of the airbag module
housing and are engaged in slots on the inside of the
cover, securely locking the trim cover into place. The
trim cover will split at predetermined breakout lines,
then fold back out of the way along with the horn
switch upon airbag deployment.
charge the gas it produces directly into the cushion
when supplied with the proper electrical signal. Fol-
lowing an airbag deployment, the airbag cushion
quickly deflates by venting this gas through the
porous fabric material used on each end panel of the
airbag cushion.
The molded plastic passenger side airbag door is
secured to extruded tabs at the top and bottom rear
of the airbag module housing by keyed openings in
the upper and lower mounting flange returns of the
airbag door. The upper and lower airbag door mount-
ing flanges are then secured to the instrument panel
structural support and the upper glove box opening
reinforcement with screws. The airbag door has pre-
determined breakout lines concealed beneath its dec-
orative cover. Upon airbag deployment, the airbag
door will split at the breakout lines and the door will
fold back over the top of the instrument panel, out of
the way.
AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is secured with
nuts to weld-studs on the ACM mounting bracket.
The ACM mounting bracket is secured with screws to
the floor panel transmission tunnel underneath the
center floor console and behind the park brake mech-
anism in the passenger compartment of the vehicle.
The ACM contains an electronic microprocessor, an
electronic impact sensor, an electromechanical safing
sensor, and an energy storage capacitor.
The ACM cannot be repaired or adjusted and, if
damaged or faulty, it must be replaced.
PASSENGER SIDE AIRBAG MODULE
DESCRIPTION
The passenger side airbag door on the instrument
panel above the glove box is the most visible part of
the passenger side airbag system. Located under the
airbag door are the passenger side airbag cushion
and the airbag cushion supporting components.
The passenger side airbag module includes an
extruded aluminum housing within which the cush-
ion and inflator are mounted and sealed. Two
stamped metal brackets, one on each end of the hous-
ing, enclose the cushion and inflator and also serve
as the mounting brackets for the module. The two
mounting brackets at the top front of the airbag mod-
ule are secured with screws to the top of the instru-
ment panel structural support beneath the
instrument panel top cover. The two mounting brack-
ets at the bottom front of the airbag module are
secured with screws to the instrument panel struc-
tural support over the glove box.
Following a passenger side airbag deployment, the
passenger side airbag module and the passenger side
airbag door must be replaced. The passenger side air-
bag module cannot be repaired, and must be replaced
if deployed or in any way damaged. The passenger
side airbag door is available as a separate service
item.
OPERATION
The microprocessor in the ACM contains the airbag
system logic. The airbag system logic includes
On-Board Diagnostics (OBD), and the ability to com-
municate with the instrument cluster circuitry over
the Chrysler Collision Detection (CCD) data bus to
control the airbag indicator lamp. The microprocessor
continuously monitors all of the airbag system elec-
trical circuits to determine the system readiness. If
the ACM detects a monitored system fault, it sends
messages to the instrument cluster over the CCD
data bus to turn on the airbag indicator lamp. Refer
to
Instrument Cluster
in the proper section of
Group 8E - Instrument Panel Systems for more infor-
mation on the airbag indicator lamp.
One electronic impact sensor is used in this airbag
system. The impact sensor is an accelerometer that
senses the rate of vehicle deceleration, which pro-
vides verification of the direction and severity of an
impact. The impact sensor is calibrated for the spe-
cific vehicle, and is only serviced as a unit with the
OPERATION
The hybrid-type inflator assembly includes a small
canister of highly compressed argon gas. The inflator
seals the hole in the airbag cushion so it can dis-
 8M - 4
PASSIVE RESTRAINT SYSTEMS
XJ
DESCRIPTION AND OPERATION (Continued)
ACM. A pre-programmed decision algorithm in the
ACM microprocessor determines when the decelera-
tion rate as signaled by the impact sensor indicates
an impact that is severe enough to require airbag
system protection. When the programmed conditions
are met, the ACM sends an electrical signal to deploy
the airbags.
In addition to the electronic impact sensor, there is
an electromechanical sensor within the ACM called a
safing sensor. The safing sensor is a normally open
series switch located in the airbag deployment circuit
of the ACM. This sensor detects impact energy of a
lesser magnitude than the electronic impact sensor,
and must be closed in order for the airbags to deploy.
The ACM also contains an energy-storage capaci-
tor. This capacitor stores enough electrical energy to
deploy the airbags for up to one second following a
battery disconnect or failure during an impact. The
purpose of the capacitor is to provide airbag system
protection in a severe secondary impact, if the initial
impact has damaged or disconnected the battery, but
was not severe enough to deploy the airbags.
However, if the clockspring is removed for service or
if the steering column is disconnected from the steer-
ing gear allowing the clockspring tape to change posi-
tion relative to the other steering components, it
must be re-centered following completion of the ser-
vice or it may be damaged. Refer to
Clockspring
Centering
in the Adjustments section of this group
for the proper centering procedures.
Service replacement clocksprings are shipped pre-
centered and with a locking pin installed. This lock-
ing pin should not be removed until the clockspring
has been installed on the steering column. If the
locking pin is removed before the clockspring is
installed on a steering column, the clockspring cen-
tering procedure must be performed.
DIAGNOSIS AND TESTING
AIRBAG SYSTEM
A DRB scan tool is required for diagnosis of the
airbag system. See the proper Diagnostic Procedures
manual for more information.
(1) Connect the DRB scan tool to the 16-way data
link wire harness connector. The connector is located
on the driver side lower edge of the instrument
panel, outboard of the steering column (Fig. 1).
CLOCKSPRING
DESCRIPTION
The clockspring assembly is secured with two inte-
gral plastic latches onto the steering column lock
housing near the top of the steering column behind
the steering wheel. The clockspring is used to main-
tain a continuous electrical circuit between the fixed
clockspring wire harness on the steering column and
several electrical components that rotate with the
steering wheel. The rotating components include the
driver side airbag module, the horn switch and, if the
vehicle
is
so
equipped,
the
vehicle
speed
control
switches.
The clockspring cannot be repaired. If the clock-
spring is faulty, damaged, or if the driver side airbag
has been deployed, the clockspring must be replaced.
OPERATION
The clockspring assembly consists of a plastic case
which contains a flat, ribbon-like, electrically conduc-
tive tape that winds and unwinds like a clockspring
with the steering wheel rotation. The electrically con-
ductive tape consists of several fine gauge copper
wire leads sandwiched between two narrow strips of
plastic film.
Like the clockspring in a timepiece, the clockspring
tape has travel limits and can be damaged by being
wound too tightly. To prevent this from occurring, the
clockspring is centered when it is installed on the
steering column. Centering the clockspring indexes
the clockspring tape to other steering components so
that it can operate within its designed travel limits.
Fig. 1 16-Way Data Link Connector - Typical
1 – 16–WAY DATA LINK CONNECTOR
2 – BOTTOM OF INSTRUMENT PANEL
(2) Turn the ignition switch to the On position.
Exit the vehicle with the DRB. Be certain that the
 XJ
PASSIVE RESTRAINT SYSTEMS
8M - 5
DIAGNOSIS AND TESTING (Continued)
DRB contains the latest version of the proper DRB
software.
(3) Using
DISPOSAL OF NON-DEPLOYED AIRBAG MODULES
All damaged or faulty and non-deployed driver side
or passenger side airbag modules which are replaced
on vehicles are to be returned. If an airbag module
assembly is faulty or damaged and non-deployed,
refer to the parts return list in the current Chrysler
Corporation Warranty Policies and Procedures man-
ual for the proper handling and disposal procedures.
the
DRB,
read
and
record
the
active
Diagnostic Trouble Code (DTC) data.
(4) Read and record any stored DTC data.
(5) See the proper Diagnostic Procedures manual if
any DTC is found in Step 3 or Step 4.
(6) After completing the necessary repairs, try to
erase the stored DTC data. If any problems remain,
the stored DTC data will not erase. See the proper
Diagnostic Procedures manual for the procedures to
diagnose any stored DTC that will not erase.
(7) With the ignition switch still in the On posi-
tion, check to be certain that nobody is in the vehicle.
(8) From outside of the vehicle (away from the air-
bags in case of an accidental deployment) turn the
ignition switch to the Off position for about ten sec-
onds, and then back to the On position. Observe the
airbag indicator lamp in the instrument cluster. It
should light for six to eight seconds, and then go out.
This indicates that the airbag system is functioning
normally.
DEPLOYED
Any vehicle which is to be returned to use after an
airbag deployment, must have both airbag modules,
the passenger side airbag module door and the clock-
spring replaced. These components will be damaged
or weakened as a result of an airbag deployment,
which may or may not be obvious during a visual
inspection, and are not intended for reuse.
Other vehicle components should be closely
inspected, but are to be replaced only as required by
the extent of the visible damage incurred.
STORAGE
An airbag module must be stored in its original,
special container until used for service. Also, it must
be stored in a clean, dry environment; away from
sources of extreme heat, sparks, and high electrical
energy. Always place or store an airbag module on a
surface with its trim cover or airbag side facing up,
to
NOTE: If the airbag indicator lamp fails to light, or
lights and stays on, there is an airbag system mal-
function.
See
the
proper
Diagnostic
Procedures
manual to diagnose the problem.
minimize
movement
in
case
of
an
accidental
SERVICE PROCEDURES
deployment.
CLEANUP PROCEDURE
Following an airbag system deployment, the vehi-
cle interior will contain a powdery residue. This res-
idue consists primarily of harmless particulate
by-products of the small pyrotechnic charge used to
initiate the airbag deployment propellant. However,
this residue will also contain traces of sodium
hydroxide powder, a chemical by-product of the pro-
pellant material that is used to generate the nitrogen
gas that inflates the airbag. Since sodium hydroxide
powder can irritate the skin, eyes, nose, or throat, be
sure to wear safety glasses, rubber gloves, and a
long-sleeved shirt during cleanup (Fig. 2).
AIRBAG SYSTEM
NON-DEPLOYED
At no time should any source of electricity be per-
mitted near the inflator on the back of an airbag
module. When carrying a non-deployed airbag mod-
ule, the trim cover or airbag side of the module
should be pointed away from the body to minimize
injury in the event of an accidental deployment. If
the module is placed on a bench or any other surface,
the trim cover or airbag side of the module should be
face up to minimize movement in the event of an
accidental deployment.
In addition, the airbag system should be disarmed
whenever any steering wheel, steering column, or
instrument panel components require diagnosis or
service. Failure to observe this warning could result
in accidental airbag deployment and possible per-
sonal injury. Refer to
Group 8E - Instrument
Panel Systems
for additional service procedures on
the instrument panel components. Refer to
Group
19 - Steering
for additional service procedures on
the steering wheel and steering column components.
WARNING: IF YOU EXPERIENCE SKIN IRRITATION
DURING CLEANUP, RUN COOL WATER OVER THE
AFFECTED AREA. ALSO, IF YOU EXPERIENCE
IRRITATION OF THE NOSE OR THROAT, EXIT THE
VEHICLE FOR FRESH AIR UNTIL THE IRRITATION
CEASES. IF IRRITATION CONTINUES, SEE A PHYSI-
CIAN.
Begin the cleanup by removing the airbag modules
from the vehicle. Refer to
Driver Side Airbag Mod-
ule
and
Passenger Side Airbag Module
in the
Â
[ Pobierz całość w formacie PDF ]