Jeep 200 Cherokee, Service Manual

Page: 510 / 2119

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.
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 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-
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.
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
XJ
PASSIVE RESTRAINT SYSTEMS 8M - 3
DESCRIPTION AND OPERATION (Continued)