Seat Belt Switch: Operation

The seat belt switches are designed to provide a status signal to the seat belt switch sense inputs of the ElectroMechanical Instrument Cluster (EMIC) indicating whether the driver side and passenger side front seat belts are fastened. The EMIC uses these inputs to control the seat belt indicator based upon the status of the driver side and passenger side front seat belt switches.

A spring-loaded plastic slide with a small, enclosed permanent magnet 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 into close proximity of 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 EMIC, which monitors the current to determine the status of the front seat belts. When the seat belt is unbuckled, the spring-loaded slide and permanent magnet move upward and away from the IC, causing the output current from the seat belt switch to be reduced.

The seat belt switch receives a supply of current from the EMIC, and the EMIC senses the status of the front seat belt through its pigtail wire connection to the seat wire harness. The EMIC also monitors the condition of the seat belt switch circuit and will store a Diagnostic Trouble Code (DTC) for any fault that is detected in the seat belt switch circuit. For proper diagnosis of the seat belt switch, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.