Seat Belt Switch - Operation

OPERATION

The front seat belt switches are designed to control a hard wired sense input to the Occupant Restraint Controller (ORC). A spring-loaded slide with a small window-like opening is integral to the buckle latch mechanism. When a seat belt tip-half is inserted and latched into the seat belt buckle, the slide is pushed downward and the window of the slide exposes the Hall Effect Integrated Circuit (IC) chip within the buckle. The field of the permanent magnet induces a current within the chip. The chip provides this induced current as an output to the ORC. When the seat belt is unbuckled, the spring-loaded slide moves upward and shields the IC from the field of the permanent magnet, causing the output current from the seat belt switch to be reduced.

The seat belt switches receive a supply of current from the ORC, and the ORC senses the status of the front seat belt switches through its connection to the seat wire harness. The ORC provides electronic seat belt switch status messages to the Instrument Cluster (IC) (also known as the Common Instrument Cluster/CIC) over the Controller Area Network (CAN) data bus. The IC uses these messages as an additional logic input for control of the seat belt indicator. The ORC monitors the condition of the seat belt switch circuits and will store a Diagnostic Trouble Code (DTC) for any fault that is detected.

The hard wired circuits between the seat belt switches 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 switches or the electronic controls or communication between other modules and devices that provide some features of the seat belt reminder system. The most reliable, efficient, and accurate means to diagnose the seat belt switches or the electronic controls and communication related to seat belt switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.