Product description Schumacher's OBDII Memory Saver Detector attaches between a portable power unit and a vehicle's on-board data (OBDII) diagnostic port, to maintain power to the vehicle's on-board microprocessor controlled devices when the vehicle's battery is disconnected for service or replacement. Fully automatic, this unit features a standard fuse protected auxiliary input plug, easy to follow 3 step instructions printed on unit, and auto detection will detect automatically if the vehicle’s electronics will allow this device to save on-board data. The LED indicators features: two yellow LEDs at each end to indicate that the OBDII port connection and the connection to the portable power unit are sound; and a red LED (do not proceed) or green LED (proceed) to indicate whether it is safe to remove or service the vehicle’s battery without fear of losing data stored in the vehicle’s microprocessor controlled devices. Works on all vehicles equipped with a standard on-board data (OBDII) port.