Occupant Classification Module: Description

Fig 1: OCCUPANT CLASSIFICATION MODULE (OCM) - TYPICAL

Courtesy of DAIMLERCHRYSLER CORP.

The Occupant Classification Module (OCM). See Fig 1 is secured with two screws to a stamped steel mounting bracket welded onto the underside of the passenger front seat cushion frame near the inboard front corner. See Fig 2. 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 software is flash programmable.

Fig 2: OCM LOCATION

Courtesy of DAIMLERCHRYSLER CORP.

A non-calibrated OCM is the only component of the Occupant Classification System (OCS) that is available for separate service replacement. The OCS components of the passenger side front seat cushion including the cushion frame, insulator pad, seat weight bladder and pressure sensor, seat cushion foam, wiring harness 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 calibrated OCM and stored in the memory of the Occupant Restraint Controller (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.

The OCM cannot be adjusted or repaired and, if damaged or faulty, it must be replaced. The components of the passenger front seat cushion are serviced only as a factory-calibrated, assembled and tamper-evident unit. Only the OCM and the seat cushion trim are available for separate service replacement. Once a service replacement package has been installed in a vehicle, the OCM can thereafter be serviced only by replacing the entire passenger front seat cushion with another complete service replacement package.