Engine Control Module: Description and Operation

The PCM is the control center of the fuel injection system. It constantly looks at the information from various sensors, and controls the systems that affect vehicle performance. The PCM performs the diagnostic function of the system. It can recognize operational problems, alert the driver through the "MALFUNCTION INDICATOR LAMP", and store a code or codes which identify the problem areas to aid the technician in making repairs. The PCM is replaced as a complete unit, there are no serviceable parts in the PCM.