Diagnosis Apparatus

A diagnosis apparatus includes a vehicle including a battery and a BMS connected to the vehicle. The vehicle is configured to generate a signal having a predetermined period and a predetermined width, and the BMS is configured to diagnose a communication state between the vehicle and the BMS and a state of the battery based on the signal, and to determine the communication state and the state of the battery as a normal state when a period of the signal is the same as a reference period and a width of the signal is the same as a reference width.