Electric pumps, electric power steering (EPS), heaters, and other electrical components have increased in number, making wiring harnesses (electrical wires) more complex and increasing vehicle weight.

Efficient use of limited electric power is also an urgent issue due to electric vehicles (EVs) and advanced driver assistance systems (ADAS).
In such cases, the conventional domain-type power supply system has been used, in which electronic control units (ECUs) are placed for each function and power is transmitted individually at a voltage of 12 V. In the current system, however, the power is supplied to each ECU by a separate power supply system, which is called a “domain-type power supply system.

However, as the number of ECUs increases, not only does the amount and weight of wires increase
This also brings to light the issue of software updates becoming more complex.