Cars Soon Will Be Speaking The Same Language

With electronics controlling everything from fuel injection to antilock brakes, the average car contains up to half a mile of wiring. To trim the wires, carmakers have embraced multiplexing, a technique for transmitting multiple control messages across a single wire at the same time. However, each carmaker's multiplexing scheme has been proprietary, making it impossible to meet an Environmental Protection Agency and California Air Resources Board requirement that cars provide a standardized means of relaying data about exhaust emissions to diagnostic scanners.

But on Jan. 25, the Society of Automotive Engineers approved a multiplexing standard, called J1850. And Harris Semiconductor has already developed microchips that comply. With each car using about 10 sets of such chips, Harris figures that demand could run as high as 100 million units a year--enough volume to save $5 to $20 per car.