Jeep 1996 Grand Cherokee Service Manual - page 398
to light the airbag indicator lamp in the instrument
cluster when a monitored airbag system fault occurs.
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.
The ACM cannot be repaired and, if damaged or
faulty, it must be replaced.
DIAGNOSIS AND TESTING
AIRBAG SYSTEM
A DRB scan tool is required for diagnosis of the
airbag system. Refer to the proper Body Diagnostic
Procedures Manual for more information.
(1) Disconnect and isolate the battery negative
cable. If the airbag system is undeployed, wait two
minutes for the system capacitor to discharge before
further service.
(2) Connect the DRB scan tool to the 16-way data
link connector. The connector is located under the
lower left corner of the instrument panel behind the
steering column cover/knee blocker (Fig. 1).
(3) Turn the ignition switch to the On position.
Exit the vehicle with the DRB. Use the latest version
of the proper DRB cartridge.
(4) After checking that nobody is inside the vehi-
cle, reconnect the battery negative cable.
(5) Using the DRB, read and record the active
Diagnostic Trouble Code (DTC) data.
(6) Read and record any stored DTC data.
(7) Refer to the proper Body Diagnostic Procedures
Manual, if any DTC is found in Step 5 or Step 6.
(8) Erase the stored DTC data, if there are no
active fault codes. If any problems remain, the stored
DTC data will not erase.
(9) With the ignition switch still in the On posi-
tion, make sure nobody is in the vehicle.
(10) From outside of the vehicle (away from the
airbag modules in case of an accidental deployment)
turn the ignition switch to the Off position, and then
back to the On position. Observe the airbag indicator
lamp in the instrument cluster. It should light for six
to eight seconds - then go out. This indicates that the
airbag system is functioning normally.
NOTE: If the airbag warning lamp fails to light, or
lights and stays on, there is a system malfunction.
Refer to the proper Body Diagnostic Procedures
Manual to diagnose the problem.
SERVICE PROCEDURES
AIRBAG SYSTEM
UNDEPLOYED
At no time should any source of electricity be per-
mitted near the inflator on the back of an airbag
module. When carrying an undeployed airbag mod-
ule, the trim cover or airbag side should be pointed
away from the body to minimize injury in the event
of accidental deployment. If the module is placed on
a bench or any other surface, the trim cover or airbag
side should be face up to minimize movement in the
event of an accidental deployment.
In addition, the airbag system should be disarmed
whenever steering wheel, steering column, or instru-
ment panel components require diagnosis or service.
Failure to observe this warning could result in acci-
dental airbag deployment and possible personal
injury. Refer to Group 8E - Instrument Panel Sys-
tems for additional service procedures on the instru-
ment panel. Refer to Group 19 - Steering for
additional service procedures on the steering wheel
and steering column.
DEPLOYED
Any vehicle which is to be returned to use after an
airbag system deployment, must have the airbag
modules, clockspring, instrument panel top pad, and
the passenger’s side airbag rear mounting bracket
replaced. These are one-time components and cannot
Fig. 1 16-Way Data Link Connector - Typical
ZJ
PASSIVE RESTRAINT SYSTEMS
8M - 3
DESCRIPTION AND OPERATION (Continued)