Reference Manual

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Chapter 10: Emissions Equpiment: Engine Control Module

The ECM (Engine Control Module) is the control center of the fuel control system. It constantly looks at the information from various sensors, and controls the systems that effect vechicle performance.

The ECM performs the dianostic function of the system. It can recognize operational problems, alert the driver though the SES (Service Engine Soon) light, and store a code or codes which identify the problem area(s) to aid the service technichian in making repairs.

The SES light on the instrument panel has two functions:

• It is used to inform the driver that a problem has occurred.
• It can be used by the service technician to display trouble codes.

The ECM supplies either 5 or 12 volts to power various sensors or switches. The ECM controls output circuits such as the Mixture Control Solenoid, EGR, Air Management, etc. by controlling the ground circuit through transistors (called Drivers) in the ECM.