Theory Of Operation-Seat Belt Switch

The seat belt sensor is an integral part of the driver and front passenger seat belt buckle. The sensor is a two-wire Hall-effect type sensor that provides the state (fastened/unfastened) of the seat belt to the Occupant Restraint Module (ORC).

A resistor is connected in parallel with the Hall-effect sensor circuits which allows a small amount of current to flow through the circuit continuously. The resistor allows the ORC to detect open circuit faults. The ORC monitors the current in the circuit. When the seat belt is unbuckled the circuit will have 5-8 mA. When the seat belt is buckled the circuit will have12-17 mA. If the harness is disconnected, the current flow is interrupted and a Diagnostic Trouble Code (DTC) is set.