Dodge Durango (HB). Manual - part 556

1. Disconnect and isolate the battery negative cable.

Wait two minutes for the system capacitor to dis-
charge before further service.

2. Reach under the front edge of the passenger side

front seat cushion to access and disconnect the
two seat wire harness connectors (3) from the
Occupant Classification Module (OCM) (4) connec-
tor receptacles located on the inboard facing side
of the module.

3. Remove the two screws (2) that secure the OCM

to the OCM bracket (1) on the underside of the
passenger side front seat cushion frame.

4. Remove the OCM from under the passenger side

front seat.

INSTALLATION

WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental
restraint system before attempting any steering wheel, steering column, airbag, occupant classification sys-
tem, seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect
and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge
before performing further diagnosis or service. This is the only sure way to disable the supplemental
restraint system. Failure to take the proper precautions could result in accidental airbag deployment.

NOTE: A non-calibrated Occupant Classification Module (OCM) is available for separate service replace-
ment. The OCM and all of the other components of the Occupant Classification System (OCS) including the
passenger side front seat, the seat weight sensors, the passenger or driver seat track position sensor and
the seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and
assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM
must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool,
and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.

1. Carefully position the Occupant Classification Mod-

ule (OCM) (4) to the OCM bracket (1) on the
underside of the passenger side front seat cushion
frame. When the OCM is correctly positioned, the
connector receptacles on the module will be
pointed inboard in the vehicle.

2. Install and tighten the two screws (2) that secure

the OCM to the OCM bracket. Tighten the screws
to 2 N·m (15 in. lbs.).

3. Reconnect the two seat wire harness connectors

(3) to the OCM connector receptacles located on
the inboard facing side of the module. Be certain
that the latches on both connectors are each fully
engaged.

4. Do not reconnect the battery negative cable at this

time. The supplemental restraint system verification
test procedure should be performed following ser-
vice of any supplemental restraint system compo-
nent. (Refer to 8 - ELECTRICAL/RESTRAINTS -
STANDARD PROCEDURE - VERIFICATION TEST).

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5. Following successful completion of the supplemental restraint system verification test procedure, perform the

Occupant Classification System Verification Test using a diagnostic scan tool. Refer to the appropriate diagnostic
procedures.

MODULE-OCCUPANT RESTRAINT CONTROLLER

DESCRIPTION

The Occupant Restraint Controller (ORC) (1) is
secured with three screws to a stamped steel mount-
ing bracket welded onto the top of the floor panel
transmission tunnel just behind the front seat cross-
member and beneath the center floor console in the
passenger compartment of the vehicle. Concealed
within a hollow in the center of the die cast aluminum
ORC housing is the electronic circuitry of the ORC
which includes a microprocessor, an electronic impact
sensor, an electronic safing sensor, 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 (3) printed on the label (2) 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 on three cor-
ners. The mounting flange to the right of the connector
receptacle has an integral locating pin on its lower
surface. Both right side flanges have round mounting
holes, while the flange on the left side has a slotted mounting hole. A molded plastic electrical connector (4) with
two receptacles, one containing twenty-four terminal pins and the other containing thirty-two terminal pins, exits the
forward facing side of the ORC housing. These terminal pins connect the ORC to the vehicle electrical system
through two dedicated take outs and connectors of the body wire harness.

The impact sensor and safing sensor internal to the ORC are calibrated for the specific vehicle, and are only ser-
viced as a unit with the ORC. In addition, there are unique versions of the ORC for vehicles with or without the
optional side 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 Controller (ORC) contains the supplemental restraint system logic
circuits and controls all of the supplemental 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 Controller Area Network (CAN) data bus. This method of communication is used for control of the airbag
indicator in the ElectroMechanical Instrument Cluster (EMIC) and for supplemental restraint system diagnosis and
testing through the 16-way data link connector located on the driver side lower edge of the instrument panel. (Refer
to 8 - ELECTRICAL/INSTRUMENT CLUSTER/AIRBAG INDICATOR - OPERATION).

The ORC microprocessor continuously monitors all of the supplemental restraint system electrical circuits to deter-
mine 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 CAN 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 DTCs, 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 forever.

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RESTRAINTS - SERVICE INFORMATION

On models equipped with the Occupant Classification System (OCS), the ORC communicates with the Occupant
Classification Module (OCM) over the CAN data bus. The ORC will internally disable the passenger airbag and seat
belt tensioner deployment circuits 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
passenger airbag on/off 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 circuits; 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 and take out of the instrument panel wire harness. This take out has
a single eyelet terminal connector that is secured by a ground screw near the center of the instrument panel struc-
tural support. 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 supplemental restraint compo-
nents for up to one second following a battery disconnect or failure. The purpose of the capacitor is to provide
backup supplemental 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 mon-
itors inputs from two remote front impact sensors located on the back of the right and left vertical members of the
radiator support near the front of the vehicle. The electronic impact sensors are accelerometers that sense the rate
of vehicle deceleration, which provides verification of the direction and severity of an impact. On vehicles equipped
with optional side curtain airbags the ORC also monitors inputs from six additional remote impact sensors located
on the left and right inner B-pillars, C-pillars and D-pillars to control deployment of the side curtain airbag units.

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 optional side curtain airbags, feature a
second safing sensor within the ORC to provide confirmation to the ORC microprocessor of side impact forces. This
second safing 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 sensors 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 air-
bag deployment 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 vehicle is so equipped, either side curtain airbag unit. 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 (passenger airbag on/off indicator Off) at the time of the impact.

The hard wired inputs and outputs for the ORC may be diagnosed and tested using conventional diagnostic tools
and procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the ORC,
the CAN data bus network, or the electronic message inputs to and outputs from the ORC. The most reliable, effi-
cient, and accurate means to diagnose the ORC, the CAN data bus, and the electronic message inputs to and
outputs from the ORC requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

REMOVAL

RESTRAINTS - SERVICE INFORMATION

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WARNING: To avoid personal injury or death, never strike or drop the occupant restraint controller, as it can
damage the impact sensor or affect its calibration. The occupant restraint controller contains the impact
sensor, which enables the system to deploy the supplemental restraints. If an occupant restraint controller
is accidentally dropped during service, the module must be scrapped and replaced with a new unit. Failure
to observe this warning could result in accidental, incomplete, or improper supplemental restraint deploy-
ment.

CAUTION: On vehicles equipped with the Occupant Classification System (OCS), never replace both the
Occupant Restraint Controller (ORC) and the Occupant Classification Module (OCM) at the same time. If
both require replacement, replace one. Then perform the supplemental restraint verification test before
replacing the other. Both the ORC and the OCM store 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.

1. Disconnect and isolate the battery negative cable.

Wait two minutes for the system capacitor to dis-
charge before further service.

2. Remove the center console from the top of the

floor panel transmission tunnel. (Refer to 23 -
BODY/INTERIOR/FLOOR

CONSOLE

REMOVAL).

3. Disconnect the two body wire harness connectors

(1) from the Occupant Restraint Controller (ORC)
(2) connector receptacles located on the forward
facing side of the module. To disconnect the wire
harness connectors from the ORC, depress the
release tab and lift the lever arm on each connec-
tor.

4. Remove the three screws (3) that secure the ORC

to the ORC bracket (4) that is welded onto the top
of the floor panel transmission tunnel.

5. Remove the ORC from the floor panel transmission

tunnel.

INSTALLATION

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RESTRAINTS - SERVICE INFORMATION

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