Sebring Sedan L4-2.4L VIN J (2004)
Body Control Module: Description and Operation
Functional Operation
Airbag System
AIRBAG SYSTEM
The JR Airbag System contains the following components: two types of Occupant Restraint Controller or (ORC), base and premium, Airbag Warning
Indicator, Clockspring, Driver and Passenger Dual Squib Airbags, Seat belt Tensioners, Left and Right Side Impact Sensors, and Curtain (roof
mounted;) Airbags. The (ORC) is a new type of Airbag Control Module (ACM) that supports staged airbag deployment. The term Airbag Control
Module or ACM will be used throughout the airbag diagnostic section and in the Diagnostic Readout Box or DRB III(R). The Base ACM can be
identified by the present of a single yellow 23 - way connector. This module supports the Driver and Passenger Seat Belt Tensioners and dual squib
airbags.
The ACM has four major functions: PCI Bus communications, onboard diagnostics, impact sensing, and component deployment. The ACM sends and/or
receives PCI Bus messages with the Instrument Cluster (MIC), Body Control Module (BCM), and Powertrain Control Module (PCM). Diagnostic
trouble codes will be set if the communication with these modules is lost or contains invalid information. If the ACM detects a monitored system fault, it
sends a message to the instrument cluster via PCI bus to turn on the Airbag Warning Indicator. The ACM can set both active and stored diagnostic
trouble codes to aid in the diagnosing system problems.
The ACM has an internal accelerometer that senses the rate of vehicle deceleration, which provides verification of the direction and severity of an
impact. A pre-programmed decision algorithm in the ACM microprocessor determines when the deceleration rate is severe enough to require airbag
system protection. The ACM also uses the crash severity to determine the level of driver and front passenger deployment, staged deployment low
medium or high. Staged deployment is the ability to trigger airbag system squib inflators all at once or individually as needed to provide the appropriate
restraint for the severity of the impact. When the programmed conditions are met, the ACM sends an electrical signal to deploy the appropriate airbag
system components. The ACM stores enough electrical energy to deploy the airbag components for two seconds following a battery disconnect or
failure during an impact.
The Premium ACM can be identified by the present of a two yellow 32 - way connectors and the presents of side curtain airbag. In addition to the base
system components and DTC's the premium ACM supports the Side Impact Sensors, side Curtain Airbags. In addition to the ACM accelerometer the
premium module uses Side Impact Sensors to identify the direction and severity of a side impact and deploy the appropriate side curtain airbag. In
addition to the base ACM DTCs the premium ACM provides DTC's for the additional circuit and component.
Both modules are secured to the floor panel transmission tunnel between the front seats inside the vehicle. Airbag Control Modules cannot be repaired or
adjusted and must be replaced.
WARNING:
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THE AIRBAG SYSTEM IS A SENSITIVE, COMPLEX ELECTROMECHANICAL UNIT. BEFORE ATTEMPTING TO DIAGNOSE
OR SERVICE ANY AIRBAG SYSTEM OR RELATED STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT 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 AND POSSIBLE PERSONAL INJURY OR DEATH.
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NEVER STRIKE OR KICK THE AIRBAG CONTROL MODULE OR SIDE IMPACT SENSORS, AS IT CAN DAMAGE THE
INTERNAL ACCELERATION SENSOR OR AFFECT ITS CALIBRATION. IF AN AIRBAG CONTROL MODULE OR SIDE
IMPACT SENSOR IS ACCIDENTALLY DROPPED DURING SERVICE, THE MODULE OR SENSOR MUST BE SCRAPPED AND
REPLACED WITH A NEW UNIT. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL
AIRBAG DEPLOYMENT AND PERSONAL INJURY OR DEATH.
The Airbag Warning Indicator 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 MCI performs a lamp check by turning the Airbag Warning Indicator on for 6-8 seconds. After the lamp check, if
the indicator turns off, it means that the ACM has checked the system and found it to be free of discernible malfunctions. If the lamp remains on, there
could be an active fault in the system or the MIC lamp circuit may be internally shorted to ground. If the lamp comes on and stays on for a period longer
than 6-8 seconds, then goes off, there is usually an intermittent problem in the system.
DRIVER AIRBAG
The airbag protective trim cover is the most visible part of the driver side airbag system. 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 module is mounted directly to the steering wheel. Located under the trim
cover are the horn switch, the airbag cushion, and the airbag cushion supporting components. The airbag module includes a housing to which the
cushion and hybrid inflator are attached and sealed. The driver airbag has dual stage squib inflators that include a small canister of highly compressed
argon gas. The ACM uses vehicle crash severity, to determine the level of airbag deployment. When supplied with the proper electrical signal, the
hybrid inflator or inflators discharge the compressed gas it contains directly into the cushion. The airbag module cannot be repaired, and must be
replaced if deployed or in any way damaged.
WARNING: THE DRIVER AIRBAG MODULE CONTAINS ARGON GAS PRESSURIZED TO OVER 17236.89 Kpa (2500 PSI). DO NOT
