Module, Occupant Classification: Description
In vehicles manufactured for domestic markets, the passenger side front seat incorporates the Occupant Classification System (OCS). The OCS consists of a single factory-calibrated unit, which includes the following components:
- Electronic Pressure Sensor - The electronic pressure sensor is integral and internal to the Occupant Classification Module (OCM) (5). Only the hose nipple for the pressure hose (4) is visible on the outside of the OCM housing (5). The remainder of the sensor and the sensor circuitry are concealed and protected within the molded black plastic OCM housing.
- Occupant Classification Module
- The OCM (5) is located on the passenger front seat structure. Concealed within a hollow in the center of the molded black plastic OCM housing is the electronic circuitry of the module. The module housing is sealed to enclose and protect the internal electronic circuitry. A connector receptacle integral to the front of the OCM housing contains terminal pins that connect the sensor to the vehicle electrical system through a dedicated take out and connector of the passenger front seat wire harness. A hose nipple formation is integral to the OCM housing.
A slot integral to the top of the OCM housing snaps over a blade on a stamped metal bracket riveted to the inboard upper seat track on models with the non-storage seat. On models with the optional storage seat, the OCM housing snaps over a blade on a molded plastic stanchion integral to the forward inboard underside of the seat cushion pan.
- Pressure Hose - Through the seat pan/suspension mat, a length of clear poly hose serves as the OCS pressure hose (4). The hose is securely clamped at one end to a hose nipple fitting that extends downward from the seat weight sensor (1 or 3), and at the opposite end to the hose nipple formation of the electronic pressure sensor integral to the outside of the OCM housing. The pressure sensor circuitry is internal and integral to the OCM (5). The pressure hose (4) is filled with the same silicone fluid that fills the seat weight sensor.
- Seat Weight Sensor
- The seat weight sensor (1 or 3) is sandwiched between the seat pan/suspension mat and the seat cushion foam. A heavy jute-like insulator pad (2) (non-storage seat only) is installed between the lower surface of the bladder (3) and the seat pan/suspension mat springs. The bladder and pad (1 or 3) are secured near the forward end to the seat cushion pan by two plastic push-in fasteners. There are two unique bladder configurations: one for the non-storage passenger front seat and another for the optional storage front seat. The storage front seat includes a small storage bin which is accessed by lifting the center insert of the seat cushion.
The bladder (1 or 3) consists of two sheets of an elastomeric material and a molded plastic hose nipple fitting. The two sheets of elastomeric material are sealed together around their perimeter and joined at numerous specific intervals within their field. The hose nipple fitting is sealed to a small round hole in the lower surface of the bladder and is pointed downward where it passes through a clearance hole in the insulator pad and extends to just below the seat cushion springs. The bladder is filled with a silicone fluid to become a pliable, quilted, resistive mat and is connected to a pressure hose that connects it to the electronic pressure sensor within the OCM unit (5).
- Seat Cushion Foam - The passenger front seat cushion foam (3) is an integral part of the factory-calibrated OCS. There are two unique foam configurations: one for the non-storage passenger front seat (5) and another for the optional storage front seat (6). The storage front seat includes a small storage bin which is accessed by lifting the center insert of the seat cushion.
All of the components that make up the OCS are a factory-calibrated and assembled unit. The OCS components cannot be adjusted or repaired and, if damaged or ineffective, they MUST BE REPLACED AS A CALIBRATED UNIT. Any time the OCS and or the seat foam, is removed or replaced for any reason, the new OCS data must be re-zeroed using a diagnostic scan tool. Refer to the appropriate diagnostic information.