Method and system to determine external power available and fault states

A method and system determines the status of an external power supply connection to an information handling system. A subsystem manager of the information handling system compares an external power source identification signal and a power available signal to determine whether external power is available, unavailable or faulty. For instance, an information handling system configured as a portable computer receives external power from an AC/DC converter along with an identification signal for the converter. A state machine running on the portable computer system's Super I/O compares the identification signal and a power available signal from an internal charger to determine state of the external power source and indicate the state to a user.