1/10/2008
By Gary Goms
We can surely count on multiplexing to proliferate throughout all vehicle lines and become a common issue in future aftermarket parts distribution and service. But only time will tell how the aftermarket will adapt.
Looking back into automotive history, it’s easy to see that the electric starter of the 1920s paved the way for generators, batteries and electric lights, becoming a permanent part of modern automotive electrical systems. In a similar fashion today, multiplexed electrical systems have led to the use of multiple on-board computers to operate numerous electronic accessories like automatic transmission, antilock brake, air bag, comfort control and other equally important sub-systems. Multiplexing addresses several drawbacks to adding multiple computers to a vehicle chassis. These drawbacks include maintaining “keep-alive” memories in computers, increasing the wiring size bundle between the computers and establishing a prioritized communications system that allows various computers to perform their functions without interference from other computers. MULTIPLEXING ADVANTAGES
Multiplexing simplifies modern electrical systems because only three wires are used to operate multiple accessories. To illustrate, a body-control computer is connected to a door module by a bus communications wire, a power wire and an optional ground wire. If the power-window button is pushed to the down position, the button comma... | 
