Seat Weight Sensor: Operation

The seat weight bladder and pressure sensor unit is designed to sense the relative weight of a load applied to the passenger side front seat cushion, which provides a logic input to the microprocessor of the Occupant Classification Module (OCM). When a load is applied to the seat cushion, fluid within the bladder becomes pressurized. These changes in bladder fluid pressure are measured by the pressure sensor under the seat cushion through the bladder tube. As the pressure within the bladder changes, the circuitry of the pressure sensor changes the output voltage of the sensor.

The pressure sensor receives a nominal five volts and a ground through dedicated hard wired circuits from the OCM. The OCM then monitors the pressure sensor output voltage on a dedicated hard wired data communication circuit. The hard wired circuits between the pressure sensor and the OCM may be diagnosed and tested using conventional diagnostic tools and procedures. However, the most reliable, efficient, and accurate means to diagnose the bladder and pressure sensor input to the OCM, and the electronic message communication between the OCM and the Airbag Control Module (ACM) requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.