A method to be implemented by a vehicle capable of communication with a portable electronic device is shown. The vehicle includes an electrical system including a power switch, and an indicating system including a processor, a wireless transmission module and an indicating unit. The method includes: controlling the electrical system to temporarily provide electric power to the indicating system when the power switch is switched from a conductive state to a non-conductive state; determining whether a wireless connection is established between the portable electronic device and the wireless transmission module. When it is determined that the wireless connection is established, activating the indicating unit to output an indication signal.