A diagnosable magnetic switch assembly and method for determining a seat occupant. A network in the assembly includes a resistor in series with a magnetic switch, and a resistor in parallel with the series combination. Such an arrangement provides distinct assembly resistance values when the magnetic switch is open or closed, and thereby provides a means for diagnosing the operational state of the diagnosable magnetic switch assembly. The diagnosable magnetic switch assembly may be included in a seat occupant indicator system that embeds the seat occupant indicator system and a magnet in a cushion of a seat assembly. When the seat assembly is occupied, the magnet is separated from the seat occupant indicator system by a sufficient distance so the seat occupant indicator system is in an open state. When an occupant sits in the seat assembly, the magnet and the seat occupant indicator system are brought closer together so that the magnetic field operate the seat occupant indicator system to a closed state. A controller measures the assembly resistance values to determine if the seat assembly is empty, occupied, or if an assembly fault state is occurring.