Town & Country V6-3.3L VIN R (2003)
Body Control Module: Description and Operation
Functional Operation
Airbag System
AIRBAG SYSTEM
The Minivan Airbag System contain the following components: Occupant Restraint Controller (ORC), Airbag Warning Indicator, Clockspring, Driver
and Passenger Airbags, Seat Belt Tensioners (SBT), Hall-effect Seat Belt Switches (SBS), Left and Right Side Airbag Control Module (SIACM), and
Seat (side-mounted) Airbags.
The Occupant Restraint Controller (ORC) is a new type of Airbag Control Module (ACM) that supports staged airbag deployment. 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. The ACM has four major functions: PCI Bus communications, onboard diagnostics, impact sensing, and component
deployment. The ACM also contains an energy-storage capacitor. This capacitor stores enough electrical energy to deploy the front airbag components
for two seconds following a battery disconnect or failure during an impact. The ORC is secured to the floor panel transmission tunnel below the
instrument panel inside the vehicle. The ACM cannot be repaired or adjusted and must be replaced.
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.
The microprocessor in the ACM monitors the impact sensor signal and the airbag system electrical circuits to determine the system readiness. The
ACM also monitors bus messages from both SIACM. If the ACM detects a monitored system fault or SIACM 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 driver and front passenger seat belt switch status (buckled or unbuckled) to determine whether or not the
seat belt tensioners should deploy. The ACM also uses the crash severity to determine the level of driver and front passenger deployment, low medium
or high. When the programmed conditions are met, the ACM sends an electrical signal to deploy the appropriate airbag system components.
WARNING: 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 IS ACCIDENTAL AIRBAG
DEPLOYMENT AND POSSIBLE PERSONAL INJURY. NEVER STRIKE OR KICK THE AIRBAG CONTROL MODULE, AS IT CAN
DAMAGE THE IMPACT SENSOR OR AFFECT ITS CALIBRATION. IF AN AIRBAG CONTROL MODULE IS ACCIDENTALLY
DROPPED DURING SERVICE, THE MODULE MUST BE 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 indicator on for 6 - 8 seconds. After the lamp check, if the
indicator turns ON, 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 Minivan is equipped with driver airbag with dual stage inflators that include a small canister
of highly compressed argon gas. The ACM uses vehicle crash severity, seat belt switch status (buckled or unbuckled) as inputs 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 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
ATTEMPT TO DISMANTLE AN AIRBAG MODULE OR TAMPER WITH ITS INFLATOR. DO NOT PUNCTURE, INCINERATE, OR
BRING INTO CONTACT WITH ELECTRICITY. DO NOT STORE AT TEMPERATURE EXCEEDING 93 °C (200 °F). REPLACE
AIRBAG SYSTEM COMPONENTS ONLY BUT INTERNAL DIFFERENCES MAY RESULT IN INFERIOR OCCUPANT
PROTECTION. THE FASTENERS, SCREWS, AND BOLTS ORIGINALLY USED FOR THE AIRBAG SYSTEM COMPONENTS HAVE
SPECIAL COATINGS AND ARE SPECIFICALLY DESIGNED FOR THE AIRBAG SYSTEM. THEY MUST NEVER BE REPLACED
WITH ANY SUBSTITUTES. ANY TIME A NEW FASTENER IS NEEDED, REPLACE IT WITH THE CORRECT FASTENERS
PROVIDED IN THE SERVICE PACKAGE OR SPECIFIED IN THE MOPAR PARTS CATALOG.
CAUTION: Deployed Front Air Bags may or may not have live pyrotechnic material within the air bag inflator. Do not dispose of 2002 Model Year
