Sensor, Occupant Detection: Operation

The Occupant Detection Sensor (ODS) acts as a simple switch to detect loads placed upon the passenger side front seat cushion. The sensor circuits are connected to and monitored by the Occupant Restraint Controller (ORC) whenever the ignition switch is in the ON position. The ORC uses an algorithm logic in monitoring the changing states of the sensor input to determine whether the seat cushion load is static or dynamic.

The ORC microcontroller continuously monitors all of the Supplemental Restraint System (SRS) electrical circuits to determine the system status and readiness. If the ORC detects a monitored system fault, it sets a Diagnostic Trouble Code (DTC). However, because the ODS input is only used for control of the passenger belt alert feature, which has no effect on SRS component features or functions, the airbag indicator is NOT  illuminated in response to a detected ODS circuit fault.

The ODS signals the ORC that a passenger is present when a minimum of 47 kg (103 lbs) of weight is placed in the seat and the ODS resistance will show 214 ohms. If the resistance of the mat decreases to 214 ohms, the ODS signal to the ORC module indicates that a passenger is present. The ORC then transmits this information to the instrument cluster over the CAN bus. The passenger is only reminded to buckle up if the passenger seat occupant minimum weight threshold, determined by the ODS, is surpassed and the seat belt buckle is not latched.

The ODS receives source current and a clean ground through dedicated sensor plus and minus circuits from the ORC. The ORC then sends the appropriate sensor status information to the Body Control Module (BCM), which uses this information as an additional logic input used for control of the seat belt indicator and the passenger belt alert feature in the Instrument Panel Cluster (IPC).

The hardwired circuits between the ODS and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the ODS or the electronic controls and communication between other modules and devices that provide some features of the passenger belt alert feature. The most reliable, efficient and accurate means to diagnose the ODS or the electronic controls and communication related to the passenger belt alert feature operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.