Vehicle diagnostic system

A vehicle diagnostic system comprising:

• a communication bus mounted on a vehicle;
• a plurality of controllers for controlling vehicle operations, the controllers being connected with each other through the communication bus;
• and
• a diagnostic equipment to collect diagnostic information from the controllers through the communication bus and to diagnose the vehicle operations;
• wherein each controller operates both in a normal mode and in a sleep mode, the normal mode being an operation mode in which all of functions are operational, and the sleep mode being an operation mode in which all of or a part of the functions excluding at least a function for receiving an wake-up instruction to return to the normal mode through the communication bus are suspended, and
• wherein at least one of the controllers is configured to send the wake-up instruction to all the other controllers in response to receiving a predetermined signal from the diagnostic equipment.