A junction box includes inputs and outputs, and electronic elements for distributing electric power, received at an input from a power source of a vehicle, to the outputs to provide power to loads of the vehicle which are connected to the outputs. The phase shifter section has an adjustable phase shift and an impedance at least partially dependent of the frequency of an input signal. The devices, methods, and programs determine whether a fuel consumption reduction effect is obtained based on the engine-start fuel consumption and the fuel consumption if idling were to be continued, and provide guidance based on the determination of whether the fuel consumption reduction effect is obtained.