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Jeep Grand Cherokee WK. Manual - part 659

1. Disconnect and isolate the battery negative cable.

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

2. Remove the quarter trim panel from the lower

C-pillar. (Refer to 23 - BODY/INTERIOR/QUARTER
TRIM PANEL - REMOVAL).

3. Remove the two screws (3) that secure the side

impact sensor (2) to the C-pillar (1).

4. Disconnect the body wire harness connector (4)

from the sensor connector receptacle.

5. Remove the sensor from the C-pillar.

INSTALLATION

FRONT

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.

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

NOTE: The front and side impact sensors are interchangeable.

1. Position the right or left front impact sensor (2) into

the engine compartment.

2. Reconnect the headlamp and dash wire harness

connector (3) to the sensor connector receptacle.

3. Carefully position the sensor onto the studs on the

back of the right or left radiator support vertical
member. Be certain that the anti-rotation pin on the
back of the sensor is engaged in the center clear-
ance hole of the radiator support and the arrow on
the sensor label is pointed forward in the vehicle.

4. Install and tighten the two nuts that secure the sen-

sor to the back of the support vertical member.
Tighten the nuts to 8 N·m (70 in. lbs.).

5. 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-

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RESTRAINTS - SERVICE INFORMATION

nent. (Refer to 8 - ELECTRICAL/RESTRAINTS - STANDARD PROCEDURE - VERIFICATION TEST).

SIDE - B-PILLAR

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

NOTE: The front and side impact sensors are interchangeable.

1. Position the side impact sensor near the inner

B-pillar.

2. Reconnect the body wire harness connector (4) to

the sensor connector receptacle.

3. Position the sensor onto the inner B-pillar. Be cer-

tain that the anti-rotation pin on the back of the
sensor is engaged in the clearance hole of the
B-pillar.

4. Install and tighten the two screws that secure the

sensor to the inner B-pillar. Tighten the screws to 8
N·m (70 in. lbs.).

5. Reinstall the lower trim onto the inside of the B-pil-

lar. (Refer to 23 - BODY/INTERIOR/B-PILLAR
LOWER TRIM - INSTALLATION).

6. 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).

RESTRAINTS - SERVICE INFORMATION

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SIDE - C-PILLAR

NOTE: The front and side impact sensors are interchangeable.

1. Position the side impact sensor (2) near the inner

C-pillar (1).

2. Reconnect the body wire harness connector (4) to

the sensor connector receptacle.

3. Position the sensor onto the inner C-pillar. Be cer-

tain that the anti-rotation pin on the back of the
sensor is engaged in the clearance hole of the
C-pillar.

4. Install and tighten the two screws (3) that secure

the sensor to the inner C-pillar. Tighten the screws
to 8 N·m (70 in. lbs.).

5. Reinstall the quarter trim panel onto the lower

C-pillar. (Refer to 23 - BODY/INTERIOR/QUARTER
TRIM PANEL - INSTALLATION).

6. Do not reconnect the battery negative cable at this

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RESTRAINTS - SERVICE INFORMATION

OCCUPANT CLASSIFICATION MODULE

DESCRIPTION

The Occupant Classification Module (OCM) (1) is
secured with two screws to a mount on the underside
of the passenger side front seat cushion frame near
the inboard front corner. Concealed within a hollow in
the center of the molded plastic OCM housing is a
microprocessor and the other electronic circuitry of the
module. The module housing is sealed to enclose and
protect the internal electronic circuitry. The OCM soft-
ware is flash programmable.

Two mounting tabs (2) and two connector receptacles
(3) are integral to the OCM housing. The connector
receptacles contain terminal pins that connect the
OCM to the vehicle electrical system through a dedi-
cated take out and connector of the passenger side
front seat wire harness, and a second take out and
connector of the body wire harness.

A non-calibrated OCM is available for separate service
replacement. The OCM and all of the other compo-
nents 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 assem-
bled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-cal-
ibrated 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.

The OCM cannot be adjusted or repaired and, if damaged or faulty, it must be replaced.

OPERATION

The microprocessor in the Occupant Classification Module (OCM) contains the Occupant Classification System
(OCS) logic circuits. The OCM uses On-Board Diagnostics (OBD) and can communicate with other electronic mod-
ules in the vehicle as well as with the diagnostic scan tool using the Controller Area Network (CAN) data bus. This
method of communication is also used for OCS diagnosis and testing through the 16-way data link connector
located on the driver side lower edge of the instrument panel.

The OCM provides voltage to the four seat weight sensors located on the corners of the passenger side front seat,
and to the seat track position sensors on the outboard passenger and driver side front seat upper seat tracks. The
OCM then monitors return inputs from each of the sensors on dedicated hard wired data communication circuits.
The seat weight sensor input allows the OCM to determine whether the passenger side front seat is occupied and
the relative size of the occupant by providing a weight-sensing reference to the load on the seat. The seat track
position sensor provides an additional logic input to the OCM microprocessor that allows it to determine the position
of the front seat passenger and driver relative to the front airbags.

Pre-programmed decision algorithms and OCS calibration allow the OCM microprocessor to determine when pas-
senger airbag protection is appropriate based upon the seat load as signaled by the seat weight sensors. When the
programmed conditions are met, the OCM sends the proper electronic occupant classification messages over the
CAN data bus to the Occupant Restraint Controller (ORC), and the ORC enables or disables the deployment cir-
cuits for the passenger front supplemental restraints. The ORC also provides a control output for the passenger
airbag on/off indicator in the instrument panel based upon the electronic occupant classification messages it
receives from the OCM.

The OCM also sends electronic driver and passenger seat track position messages to the ORC over the CAN data
bus. The ORC uses the seat track position data as an additional logic input for determining the force level with
which to deploy the multistage front airbags.

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

RESTRAINTS - SERVICE INFORMATION

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