In 1970 the average car had only $25 worth of electronics. That figure reached over $3,500 by 1996. Today that figure has reached over $6,000. The figure will continue to rise with the installation of up to 40 different computers on certain vehicles.
Vehicles' computers operate everything from air conditioning, radios, air bags, alarm systems, anti-lock braking systems, traction control, ride control, cruise control, analog and digital gauges, automatic transmissions, emission and engine controls. These computers can cost from $250 to as much as $1,500 depending on what they control.
Instead of using proper diagnostic procedures, some do-it-yourselfers and shops without the technical experience resort to trial and error parts swapping when they don't know how to repair computer and performance issues. Since car dealers and parts suppliers refuse to allow the return of electronic components (due to possible damage) that may leave you, the consumer, with expensive parts you didn't need. In fact, manufacturers have reported that 80% of all returned computers were found to be okay.