In-vehicle load control system

An in-vehicle load control system configured to controllably drive one or more loads on a vehicle according to an input signal output by an operating switch or a sensor on the vehicle, the in-vehicle load control system comprising:

• a first electronic control portion configured to perform signal processing based on the input signal;
• a second electronic control portion configured to controllably drive the load;
• a multiplex communication portion configured to enable multiplex communication of information between the first electronic control portion and the second electronic control portion;
• and
• a backup signal channel independent of a signal channel through which a signal is transmitted in the multiplex communication portion, and configured to input the input signal to the second electronic control portion, wherein
• the second electronic control portion is configured to refer to a state of an ignition signal of the vehicle;
• and
• the second electronic control portion receives a first control signal via the signal channel in the multiplex communication portion and a second control signal via the backup signal channel, and controllably drives the load by preferentially treating the first control signal when the ignition signal is on and by preferentially treating the second control signal when the ignition signal is off.