This article reviews the development of multiplexed harnesses designed to replace conventional wiring looms in cars. Multiplexing is the ability to send many signals along one wire virtually simultaneously without them becoming confused. In practice this means, for example, that switches on the dashboard of a vehicle need only a couple of signal wires to control a dozen lights. This substantially reduced the quantity of wiring compared with conventional looms and provides the opportunity for engineers to add more electronics, such as radar to warn of approaching vehicles. The new multiplexed looms will have a series of modules wired in, each containing an integrated circuit mounted beside some electrics, such as load switches controlling lights, wipers, heating, etc. Microprocessors, programmability, optical fibres and the effect of electromagnetic interference (EMI) are mentioned.
Abstract