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GENERAL INFORMATION
respond to messages "addressed" to it through a
binary coding process. This method of data trans-
mission significantly reduces the complexity of the
wiring in the vehicle and the size of wiring har-
nesses. All of the information about the functioning
of all the systems is organized, controlled 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 DRBIII . Next, look for the symp-
tom in the Diagnostic Information and Procedures
section of the Table of Contents located in the front
of the book. This will direct you to the specific tests
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 2004 JR Powertrain Diagnostic Manual for
more information. Erase codes in all modules.
3.1 AIRBAG SYSTEM
The JR Airbag System contains the following
components: two types of Occupant Restraint Con-
troller or (ORC), base and premium, Airbag Warn-
ing 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 Mod-
ule or ACM will be used throughout the airbag
diagnostic section and in the Diagnostic Readout
Box or DRB III . 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 sens-
ing, and component deployment. The ACM sends
and/or receives PCI Bus messages with the Instru-
ment 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 informa-
tion. 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 prob-
lems. See DIAGNOSTIC TROUBLE CODES in this
section.
The ACM has an internal accelerometer that
senses the rate of vehicle deceleration, which pro-
vides verification of the direction and severity of an
impact. A pre-programmed decision algorithm in
the ACM microprocessor determines when the de-
celeration 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 me-
dium 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 elec-
trical energy to deploy the airbag components for
two seconds following a battery disconnect or fail-
ure 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 Cur-
tain 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 com-
ponent.
Both modules are secured to the floor panel
transmission tunnel between the front seats inside
the vehicle. Airbag Control Modules cannot be re-
paired or adjusted and must be replaced.
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