On-board power supply system and on-board control apparatus

An on-board power supply system comprising:

• at least two electronic control units each including a controller and a power source box, the controller is connected to an electrical device mounted in a vehicle via a signal line and that is configured to control an operation of the corresponding electrical device, and the power source box is connected to a power source mounted in the vehicle via a power line, the power source box is connected to the electrical device mounted in the vehicle via the power line, and the power source box is configured to switch between supply and non-supply of power from the power source to the electrical device,
• wherein, the electrical device that is to be controlled by the controller included in one of the at least two electronic control units is connected to the power source box of the other of the at least two electronic control units, and
• the power source box included in the other of the at least two electronic control units is configured to switch between supply and non-supply of power to the electrical device that is connected to the other of the at least two electronic control units, in response to a switching command from the controller included in the one of the at least two electronic control units.