After the UltraBlock SCSI bridge is turned ON, it begins scanning the SCSI bus searching for a device. If the SCSI device is ready for operation, the UltraBlock turns ON the SCSI Detect light. If the SCSI device is not ready, the UltraBlock flashes the SCSI Detect LED until the SCSI device reports that it is ready for operation. If the SCSI Detect LED never stops flashing that most likely means the SCSI device is malfunctioning.