Engine Control Module: Description and Operation
1988-89The SMEC houses circuits needed to power the ignition coil, alternator field and fuel injector, and energizes the automatic shutdown (ASD) relay. The SMEC also receives a signal from the distributor. If no distributor signal is received, the ASD relay is not activated and power is shut off from the fuel pump and ignition coil. A voltage converter in the SMEC reduces battery voltage to a regulated 8 volt output which powers the distributor.
The SMEC is a digital computer which contains a microcompressor. Input signals from various switches, sensors and components are sent to the SMEC, which then computes the fuel injector pulse width, spark advance, ignition coil dwell, idle speed, purge, cooling fan turn on and alternator charge rate.