Occupant Classification System: Notes

A non-calibrated Occupant Classification Module (OCM) is the only component of the Occupant Classification System (OCS) that is available for separate service replacement, as outlined in the procedures that follow. The OCS components of the passenger side front seat cushion including the cushion frame, springs, pad, seat weight bladder and pressure sensor, seat cushion foam and the OCM are a factory-calibrated and assembled unit. Once this unit is connected to a vehicle electrically, the calibration settings are uploaded from the OCM and stored in the memory of the Airbag Control Module (ORC). If only the OCM is subsequently replaced, the new, non-calibrated OCM learns the proper calibration settings from the ORC after it is connected to the vehicle electrically. If any of the remaining OCS components of the passenger side, front seat cushion require replacement, they are serviced only as a factory calibrated, assembled, and tamper-evident service replacement package. This package includes the assembled frame, springs, pad, seat weight bladder and pressure sensor, foam, wiring and a calibrated OCM. When installing this package, always replace all of the existing components with the new components as a unit. Do not attempt to separate or disconnect any of the new OCS components contained in the service replacement package from each other, and do not attempt to reuse any of the replaced components in this or any other vehicle. Once any of the original factory-installed components except the OCM have been replaced with the service replacement package components, the OCM can only be serviced by replacing the entire passenger side front seat cushion unit with another complete service replacement package.

CAUTION: On vehicles equipped with the Occupant Classification System (OCS), never replace both the Airbag Control Module (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.

The OCM is subsystem of the Airbag Control Module (ORC). Therefore the OCM bus message updates the ORC with the front passenger seat information via PCI Bus message. The ORC then controls the Passenger Off indicator and the Airbag Warning Indicator to provide system onboard diagnostic feedback. All OCS wiring repairs are prohibited; when wiring problems are diagnosed a Bladder Repair Kit is the only approved repair.