The automobiles of today are required to perform a multitude of electronic functions, and the list is still growing with only a limited amount of space available. The auto makers are forced to miniaturize nearly every component used in today's design. The ECM is not immune to this shrinkage, and the surface mount style of circuit design is employed in an increasing number of fuel injected vehicles. Surface mount componentry is constructed exactly as it sounds, i.e. the parts simply lie on top of the board connected only by the solder that connects it to the circuit.

While this construction is fine for personal computers and communication devices, the automotive environment is providing to be too harsh for this design to survive without some type of failure. Some of the causes of surface mount failure are: vibration, temperature, moisture, corrosion, adhesion, and incorrect alignment of parts. The technician servicing a vehicle with a surface mount ECM should be alert to the symptoms of a "hardware" failure. These problems are typically one or more of the following:

1. Intermittent failures
2. Condition failures (vibration, temperature, humidity)
3. "Gremlins" or changing symptoms
4. Impossible operating conditions

Hopefully, the auto industry will make the necessary changes to correct these design problems, but for now it's something we will have to live with.