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Chrysler RG Voyager. Manual - part 756

anchor. The OCM then monitors the return voltage
from each of the sensors. The bladder pressure sen-
sor input allows the OCM to determine whether the
passenger front seat is occupied and the relative size
of the occupant by providing a weight-sensing refer-
ence to the load on the seat cushion. The belt tension
sensor provides an additional logic input to the OCM
microprocessor that allows it to distinguish between
the lower seat belt cinch loads of a belted occupant
and the higher loads associated with a belted child
seat.

Pre-programmed decision algorithms and OCS cal-

ibration allow the OCM microprocessor to determine
when the seat cushion load as signaled by the blad-
der pressure sensor and the seat belt cinch load as
signaled by the belt tension sensor indicate that pas-
senger airbag protection is appropriate. When the
programmed conditions are met, the OCM sends the
proper electronic occupant classification messages
over the PCI data bus to the Occupant Restraint
Controller (ORC), and the ORC enables or disables
the deployment circuits for the passenger front sup-
plemental restraints. The ORC also provides a con-
trol output for the Passenger Airbag Disabled (PAD)
indicator in the instrument panel center stack, based
upon the electronic occupant classification messages
it receives from the OCM.

The OCM microprocessor continuously monitors all

of the OCS electrical circuits and components to
determine the system readiness. If the OCM detects
a monitored system fault, it sets an active and stored
Diagnostic Trouble Code (DTC) and sends the appro-
priate electronic messages to the ORC over the PCI
data bus. Then the ORC sets a DTC and sends mes-
sages to control the airbag indicator operation
accordingly. An active fault only remains for the
duration of the fault, or in some cases for the dura-
tion of the current ignition switch cycle, while a
stored fault causes a DTC to be stored in memory by
the OCM and the ORC. For some DTC’s, if a fault
does not recur for a number of ignition cycles, the
OCM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.

The OCM receives battery current from an IPM

high side driver (Run/Start). The OCM receives
ground through a ground circuit of the body wire
harness, which it shares with the ORC. These con-
nections allow the OCM to be operational whenever
the ignition switch is in the Start or ON positions.

To diagnose and test the OCS, use a scan tool and

the appropriate diagnostic information.

REMOVAL

Once any of the original factory-installed compo-

nents except the Occupant Classification Module

(OCM) have been replaced with the service replace-
ment package components, the OCM can only be ser-
viced by replacing the entire passenger front seat
cushion unit with another complete service replace-
ment package (Refer to 23 - BODY/SEATS/SEAT
CUSHION - FRONT - REMOVAL).

WARNING:

Never

replace

both

the

Occupant

Restraint Controller (ORC) and the Occupant Clas-
sification Module (OCM) at the same time. If both
require replacement, replace one, then perform the
Airbag System test (Refer to 8 - ELECTRICAL/RE-
STRAINTS - DIAGNOSIS AND TESTING - AIRBAG
SYSTEM) before replacing the other. Both the ORC
and the OCM store Occupant Classification System
(OCS) calibration data, which they transfer to one
another when one of them is replaced. If both are
replaced at the same time, an irreversible fault will
be set in both modules and the OCS may malfunc-
tion and result in personal injury or death.

(1) Disconnect and isolate the battery negative

cable.

WARNING: Wait two minutes for the airbag system
reserve capacitor to discharge before beginning
any airbag system or component service. Failure to
do so may result in accidental airbag deployment,
personal injury or death.

(2) Reach under the front edge of the passenger

side front seat cushion to access and remove the lock
pin from the connector lock tower on the Occupant
Classification Module (OCM) (Fig. 36).

(3) Disconnect the passenger front seat wire har-

ness connector for the OCM.

(4) Remove the two screws that secure the OCM to

the OCM bracket.

(5) Remove the OCM from under the passenger

front seat.

INSTALLATION

WARNING: To avoid personal injury or death on
vehicles equipped with the Occupant Classification
System (OCS), only the Occupant Classification
Module (OCM) and the seat cushion trim may be
serviced separately. All other components of the
passenger front seat cushion must be serviced only
as a complete factory-calibrated, assembled and
tamper-evident service replacement package.

Once any of the original factory-installed compo-

nents except the OCM have been replaced with the
service replacement package components, the OCM
can only be serviced by replacing the entire passen-
ger side front seat cushion unit with another com-

RESTRAINTS

8O - 25

OCCUPANT CLASSIFICATION MODULE (Continued)

plete service replacement package. (Refer to 23 -
BODY/SEATS/SEAT

CUSHION

FRONT

REMOVAL).

WARNING:

Never

replace

both

the

Occupant

(1) Carefully position the Occupant Classification

Module (OCM) to the OCM bracket (Fig. 36). When
the OCM is correctly positioned, the connector on the
module will be pointed to right side of the vehicle.

(2) Install the two screws to the OCM. Torque the

screws to 2 N·m (20 in. lbs.).

(3) Connect the seat wire harness connector for the

OCM. Be certain that the latches on the connector
are each fully engaged.

(4) Install the lock pin into the connector lock

tower on the OCM.

WARNING: Do not connect the battery negative
cable (Refer to 8 - ELECTRICAL/RESTRAINTS -
DIAGNOSIS AND TESTING - AIRBAG SYSTEM). Per-
sonal injury or death may result if the system test
is not performed first.

WARNING: Following successful completion of the
Airbag System test procedure, the Occupant Classi-
fication System Verification Test must be done
using a scan tool and the appropriate diagnostic
information.

(5) Verify vehicle and system operation.
(6) Close hood.

OCCUPANT RESTRAINT
CONTROLLER

DESCRIPTION

The Occupant Restraint Controller (ORC) (Fig. 37)

is also sometimes referred to as the Airbag Control
Module (ACM).

Fig. 36 OCM - REMOVE/INSTALL

1 - OCCUPANT CLASSIFICATION MODULE (OCM)
2 - LOCK TOWER
3 - LOCK PIN
4 - CONNECTOR
5 - SCREW (2)
6 - BRACKET

Fig. 37 OCCUPANT RESTRAINT CONTROLLER -

TYPICAL

1 - ORC
2 - ORIENTATION ARROW UPON INSTALLATION
3 - LABEL
4 - ORC ELECTRICAL CONNECTORS

8O - 26

RESTRAINTS

OCCUPANT CLASSIFICATION MODULE (Continued)

The ORC is secured with screws to a stamped steel

mounting bracket welded onto the top of the floor
panel transmission tunnel just behind and under-
neath the instrument panel center stack in the pas-
senger

compartment

the

vehicle

(Fig.

38).

Concealed within a hollow in the center of the die
cast aluminum ORC housing is the electronic cir-
cuitry of the ORC which includes a microprocessor,
an electronic impact sensor, an electronic safing sen-
sor, and an energy storage capacitor. A stamped
metal cover plate is secured to the bottom of the
ORC housing with four screws to enclose and protect
the internal electronic circuitry and components.

An arrow printed on the label on the top of the

ORC housing provides a visual verification of the
proper orientation of the unit, and should always be
pointed toward the front of the vehicle. The ORC
housing has integral mounting flanges. the ORC has
two molded plastic electrical connectors that exits the
right facing side of the ORC housing. These terminal
pins connect the ORC to the vehicle electrical system.

The impact sensor and safing sensor internal to

the ORC are calibrated for the specific vehicle, and
are only serviced as a unit with the ORC. In addi-
tion, there are unique versions of the ORC for vehi-
cles with or without curtain airbags. The ORC cannot
be repaired or adjusted and, if damaged or faulty, it
must be replaced.

OPERATION

The microprocessor in the Occupant Restraint Con-

troller (ORC) contains the supplemental restraint
system logic circuits and controls all of the supple-
mental restraint system components. The ORC uses
On-Board Diagnostics (OBD) and can communicate

with other electronic modules in the vehicle as well
as with the diagnostic scan tool using the Program-
mable Communication Interface (PCI) data bus. This
method of communication is used for control of the
airbag indicator in the ElectroMechanical Instrument
Cluster (EMIC) and for supplemental restraint sys-
tem diagnosis and testing through the 16-way Data
Link Connector (DLC) located on the driver side
lower edge of the instrument panel.

The ORC microprocessor continuously monitors all

of the supplemental restraint system electrical cir-
cuits to determine the system readiness. If the ORC
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the EMIC over the PCI data
bus to turn on the airbag indicator. An active fault
only remains for the duration of the fault, or in some
cases for the duration of the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the ORC. For some DTC’s, if a fault
does not recur for a number of ignition cycles, the
ORC will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.

On models equipped with the Occupant Classifica-

tion System (OCS), the ORC communicates with the
Occupant Classification Module (OCM) over the PCI
data bus. The ORC will internally disable the pas-
senger airbag and seat belt tensioner deployment cir-
cuits if the OCM detects that the passenger side
front seat is unoccupied or that it is occupied by a
load that is inappropriate for an airbag deployment.
The ORC also provides a control output to the Pas-
senger Airbag Disabled (PAD) indicator through the
passenger airbag indicator driver circuit. The OCM
notifies the ORC when it has detected a monitored
system fault and stored a DTC in its memory for any
faulty OCS component or circuit, then the ORC sets
a DTC and controls the airbag indicator operation
accordingly.

The ORC receives battery current through two cir-

cuits; a fused ignition switch output (RUN) circuit
through a fuse in the Junction Block (JB), and a
fused ignition switch output (RUN/START) circuit
through a second fuse in the JB. The ORC receives
ground through a ground circuit of the instrument
panel wire harness. These connections allow the ORC
to be operational whenever the ignition switch is in
the START or ON positions.

The ORC also contains an energy-storage 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 sup-
plemental restraint components for up to one second
following a battery disconnect or failure. The purpose
of the capacitor is to provide backup supplemental

Fig. 38 ORC LOCATION

1 - ORC ELECTRICAL CONNECTORS
2 - ORC
3 - ORC MOUNTING SCREWS

RESTRAINTS

8O - 27

OCCUPANT RESTRAINT CONTROLLER (Continued)

restraint system protection in case there is a loss of
battery current supply to the ORC during an impact.

Two sensors are contained within the ORC, an

electronic impact sensor and a safing sensor. The
ORC also monitors inputs from eight remote impact
sensors. Two front impact sensors are located on each
outboard side of the lower radiator support, and
three side impact sensors are located on each side of
the vehicle at the B-pillar, in the lower sliding door
opening in front of the C-pillar, and over the rear
wheel well between the C and D-pillars. The elec-
tronic impact sensors are accelerometers that sense
the rate of vehicle deceleration, which provides veri-
fication of the direction and severity of an impact.

The safing sensor is an electronic accelerometer

sensor within the ORC that provides an additional
logic input to the ORC microprocessor. The safing
sensor is used to verify the need for a supplemental
restraint deployment by detecting impact energy of a
lesser magnitude than that of the primary electronic
impact sensors, and must exceed a safing threshold
in order for the airbags to deploy. Vehicles equipped
with curtain airbags, there is a second safing sensor
within the ORC to provide confirmation to the ORC
microprocessor of side impact forces. This second saf-
ing sensor is a bi-directional unit that detects impact
forces from either side of the vehicle.

Pre-programmed decision algorithms in the ORC

microprocessor determine when the deceleration rate
as signaled by the impact sensors and the safing sen-
sors indicate an impact that is severe enough to
require supplemental restraint system protection
and, based upon the severity of the monitored
impact, determines the level of front airbag deploy-
ment force required for each front seating position.
When the programmed conditions are met, the ORC
sends the proper electrical signals to deploy the dual
multistage front airbags at the programmed force
levels, the front seat belt tensioners and, if the vehi-
cle is so equipped, either curtain airbag. For vehicles
equipped with the OCS, the passenger front airbag
and seat belt tensioner will be deployed by the ORC
only if enabled by the OCM messages (PAD indicator
OFF) at the time of the impact.

To diagnose and test the ORC and all airbag sys-

tem components, use a scan tool and the appropriate
diagnostic information.

REMOVAL

WARNING:

Never

replace

both

the

Occupant

SYSTEM) before replacing the other. Both the ORC
and the OCM store Occupant Classification System
(OCS) calibration data, which they transfer to one
another when one of them is replaced. If both are
replaced at the same time, an irreversible fault will
be set in both modules and the OCS may malfunc-
tion and result in personal injury or death.

(1) Disconnect and isolate the battery negative

cable.

(2) Remove storage bin from instrument panel

(Refer to 23 - BODY/INSTRUMENT PANEL/STOR-
AGE BIN - REMOVAL).

(3) Remove three bolts holding ORC to floor

bracket (Fig. 39).

(4) Disconnect the wire connectors from the ORC

(Fig. 39).

(5) Remove the ORC from vehicle.

INSTALLATION

WARNING: Do not install ORC if mounting location
is deformed or damaged. This will cause the ORC
to be improperly located and could result in occu-
pant personal injury or death.

WARNING: Use correct screws when installing the
ORC.

Fig. 39 ORC - REMOVE/INSTALL

1 - ORC ELECTRICAL CONNECTORS
2 - ORC
3 - ORC MOUNTING SCREWS

8O - 28

RESTRAINTS

OCCUPANT RESTRAINT CONTROLLER (Continued)

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