Just a single decade ago, many industry experts speculated that 80% of the workflow passing through an independent repair shop would involve some type of high-level diagnostic process. Today, it's obvious that, with the infusion of electronic operating systems, high-level diagnostics is now approaching that level of total workflow. Nevertheless, many others continue to ridicule the idea because everybody "knows," for example, when a PCM is shot, or when the overdrive in an automatic transmission is slipping, or when a spark plug wire goes open-circuit. Who needs a diagnostic procedure to know that stuff?

In today's technical climate, many of these same shop owners are now facing a "Diagnostic Dilemma" of their own. Their technicians may be having an increasingly difficult time diagnosing "simple" failures, such as engines that won't crank, interior lights that won't go out and warning chimes that mysteriously sound off going down the highway. As one might suspect, many shop owners haven't come to grips with the fact that a powertrain control module (PCM), body control module (BCM) or a dedicated control module now controls cranking operations, convenience items and safety equipment. To make the situation even more challenging, multiplexed electrical systems are now using inputs from a variety of powertrain and chassis sensors to control simple functions as when the rear hatch lock disengages on a modern SUV. Isn't anythi...