Removal - Chrysler Vehicle User Manual

TJ
AIRBAG CONTROL MODULE (Continued)
The ACM receives battery current through two cir-
cuits; a fused ignition switch output (run) circuit
through a fuse in the fuse block, and a fused ignition
switch output (run-start) circuit through a second
fuse in the fuse block. The ACM receives ground
through a ground circuit and take out of the body
wire harness. This take out has a single eyelet ter-
minal connector that is secured by a ground screw to
the right cowl side inner panel below the instrument
panel. These connections allow the ACM to be opera-
tional whenever the ignition switch is in the Start or
On positions. The ACM also contains an energy-stor-
age 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 front supplemental restraint components
for up to one second following a battery disconnect or
failure. The purpose of the capacitor is to provide
backup supplemental restraint system protection in
case there is a loss of battery current supply to the
ACM during an impact.
Two sensors are contained within the ACM; an
electronic impact sensor, and a safing sensor. The
electronic 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 safing sensor is an electromechanical
sensor within the ACM that provides an additional
logic input to the ACM microprocessor. The safing
sensor is a normally open switch that is used to ver-
ify the need for a front supplemental restraint
deployment by detecting impact energy of a lesser
magnitude than that of the electronic impact sensor,
and must be closed in order for the front airbags to
deploy. A pre-programmed decision algorithm in the
ACM microprocessor determines when the decelera-
tion rate as signaled by the impact sensor and the
safing sensor indicate an impact that is severe
enough to require front supplemental restraint sys-
tem protection and, based upon the status of the pas-
senger airbag on/off switch input and the severity of
the monitored impact, determines what combination
of front airbag deployment is required for each front
seating position. When the programmed conditions
are met, the ACM sends the proper electrical signals
to deploy the dual front airbags.
The hard wired inputs and outputs for the ACM
may be diagnosed and tested using conventional
diagnostic tools and procedures. However, conven-
tional diagnostic methods will not prove conclusive in
the diagnosis of the ACM, the PCI data bus network,
or the electronic message inputs to and outputs from
the ACM. The most reliable, efficient, and accurate
means to diagnose the ACM, the PCI data bus net-
work, and the electronic message inputs to and out-
puts from the ACM requires the use of a DRBIII
scan tool. Refer to the appropriate diagnostic infor-
mation.

REMOVAL

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE SYSTEM CAPACITOR TO DISCHARGE BEFORE
PERFORMING FURTHER DIAGNOSIS OR SERVICE.
THIS IS THE ONLY SURE WAY TO DISABLE THE
SUPPLEMENTAL RESTRAINT SYSTEM. FAILURE TO
TAKE THE PROPER
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
WARNING: THE AIRBAG CONTROL MODULE CON-
TAINS THE IMPACT SENSOR, WHICH ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE AIRBAG CONTROL MODULE, AS IT CAN DAM-
AGE THE IMPACT SENSOR OR AFFECT ITS CALI-
BRATION. IF AN AIRBAG CONTROL MODULE IS
ACCIDENTALLY DROPPED DURING SERVICE, THE
MODULE MUST BE SCRAPPED AND REPLACED
WITH A NEW UNIT. FAILURE TO OBSERVE THIS
WARNING COULD
INCOMPLETE, OR IMPROPER FRONT SUPPLEMEN-
TAL RESTRAINT DEPLOYMENT AND POSSIBLE
OCCUPANT INJURIES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Pull the carpet on the right and left sides of
the floor panel transmission tunnel rearward far
enough to access the Airbag Control Module (ACM),
which is forward of the floor console.
(3) On models equipped with the optional Anti-lock
Brake System (ABS), remove the acceleration switch
from the left side of the mounting bracket on the
floor panel transmission tunnel. (Refer to 5 -
BRAKES/ELECTRICAL/G-SWITCH - REMOVAL).
RESTRAINTS
PRECAUTIONS
RESULT IN ACCIDENTAL,
8O - 9
COULD