Multiplexing System for Reduced Wire Harness Size

Tatsuya Yoshida, Automotive Products Division, Hitachi, Ltd.
Shigeru Oho, Hitachi Research Laboratory, Hitachi, Ltd.


One of the challenges presented to car makers these days is how to combat the ever-increasing size of wire harnesses due to the rapid expansion of convenience-oriented electrical car body functions, including power seats, power mirrors, and power windows.

In response to this challenge, Hitachi has joined with Nissan Motor Co., Ltd. to develop a multiplexing system, which reduces wire harness size effectively.

This system integrates the electronics units for each function into a body control module (BCM) and local control units (LCUs).

The BCM receives switch signals from the LCU through a data communications line and sends drive signals to motors, lamps, and other loads connected to the LCU, thus controlling the electrical car body functions centrally.

This reduces the size of wire harnesses both in number of wires and weight. Another advantage is that the BCM controls all signals collectively, thus automating troubleshooting.

© Hitachi, Ltd. All rights reserved.