Airbag System - Chrysler Concorde 2004 Service Manual

GENERAL INFORMATION
tion about the operation of vehicle components and
circuits is relayed quickly to the appropriate mod-
ule(s). All modules receive all the information trans-
mitted on the bus even though a module may not
require all information to perform it's function. It
will only respond to messages "addressed" to it
through a binary coding process. This method of
data transmission significantly reduces the com-
plexity of the wiring in the vehicle and the size of
wiring harnesses. All of the information about the
functioning of all the systems is organized, con-
trolled, and communicated by the PCI bus, which is
described in the Vehicle Communication section of
this general information.
Always begin by reading the diagnostic trouble
codes using the DRB. Next, look for the symptom in
the Diagnostic Information and Procedures section
of the Table Of Content located in the front of the
book. This will direct you to the specific test(s) that
must be performed.
Important Note:
If the Powertrain Control Module has been
changed and the correct VIN and mileage have not
been programmed, a DTC will be set in the Airbag
module. In addition, if the vehicle is equipped with
a Sentry Key Immobilizer Module (SKIM), Secret
Key data must be updated to enable starting. Refer
to the 2003 LH Powertrain Diagnostic Manual for
more information. Erase codes in all modules.

3.1 AIRBAG SYSTEM

The Airbag System is equipped with a new type of
Airbag Control Module (ACM) called an Occupant
Restraint Controller (ORC). The ACM is secured to
a bracket on the floor panel transmission tunnel
below the instrument panel inside the vehicle. The
ACM mounting bracket also serves as the instru-
ment panel center support. The ACM contains a
microprocessor, the impact sensor, and energy stor-
age capacitors. The microprocessor contains the
airbag system logic. The airbag system logic in-
cludes On-Board Diagnostics ACM capability, and
communicates with the instrument cluster circuitry
on the Programmable Communication Interface
(PCI) data bus to control the airbag indicator lamp.
The microprocessor in the ACM monitors the im-
pact sensor signal and the airbag system electrical
circuits to determine the system readiness. If the
ACM detects a monitored system fault, it sends
messages to the Mechanical Instrument Cluster
(MIC) over the PCI data bus to turn on the airbag
warning lamp. A pre-programmed decision algo-
rithm in the ACM microprocessor determines when
the deceleration rate is severe enough to require
airbag system protection. When the programmed
conditions are met, the ACM sends an electrical
signal to deploy the airbag system components. The
impact sensor is an accelerometer that senses the
rate of vehicle deceleration, which provides verifi-
cation of the direction and severity of an impact.
The impact sensor is calibrated for the specific
vehicle, and is only serviced as a unit with the ACM.
The ACM also contains an energy-storage capacitor.
This capacitor stores enough electrical energy to
deploy the airbags, for two minutes following a
battery disconnect or failure during an impact. The
purpose of the capacitor is to provide airbag system
protection in severe secondary impact if the initial
impact has damaged or disconnected the battery,
but not severe enough to deploy the airbags. The
ACM cannot be repaired or adjusted and, if dam-
aged or faulty, it must be replaced
WARNING: THE AIRBAG SYSTEM IS A
SENSITIVE, COMPLEX
MECHANICAL UNIT. BEFORE ATTEMPTING
TO DIAGNOSE OR SERVICE ANY AIRBAG
SYSTEM OR RELATED STEERING WHEEL,
STEERING COLUMN,
PANEL COMPONENTS YOU MUST FIRST
DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE. WAIT TWO
MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE FURTHER SYSTEM
SERVICE. THIS IS THE ONLY SURE WAY TO
DISABLE THE AIRBAG SYSTEM. FAILURE
TO DO THIS COULD RESULT IN ACCIDENTAL
AIRBAG DEPLOYMENT
PERSONAL INJURY. NEVER STRIKE OR
KICK THE AIRBAG CONTROL MODULE, AS
IT CAN DAMAGE THE IMPACT SENSOR OR
AFFECT ITS
OCCUPANT RESTRAINT CONTROLLER IS
ACCIDENTALLY
SERVICE, THE
SCRAPPED AND REPLACED WITH A NEW
UNIT.
The airbag warning lamp is the only point at
which the customer can observe "symptoms" of a
system malfunction. Whenever the ignition key is
turned to the "run" or "start" position, the MIC
performs a lamp check by turning the AIRBAG
warning lamp on for 6-8 seconds. If the lamp
remains off, it means that the ACM has checked the
system and found it to be free of discernible mal-
functions. If the lamp remains on, there could be an
active fault in the ACM system or the MIC lamp
circuit may be internally shorted to ground.
3.1.1 DRIVER AIRBAG (DAB)
The airbag protective trim cover is the most
visible part of the driver side airbag system. The
airbag is mounted directly to the steering wheel.
2
ELECTRO-
OR INSTRUMENT
AND POSSIBLE
CALIBRATION. IF
DROPPED DURING
MODULE MUST
AN
BE