Engine Control Module: Description and Operation
1988-89The SMEC contains circuits necessary to energize the ignition coil, fuel injectors and alternator field in order to minimize electrical noise in the passenger compartment. The SMEC is a digital computer containing a microprocessor. This module receives input signals from various switches and sensors. It then computes fuel injector pulse width, spark advance, ignition coil dwell, idle speed, purge, and cooling fan turn on and alternator charge rate.
The Automatic Shut Down (ASD) relay, mounted externally, is turned On and Off by the SMEC in response to distributor pickup signal. If no distributor signal is present, the ADS relay is not activated and power is shut off from fuel injector and ignition coil. The SMEC contains a voltage converter which converts battery voltage to a regulated 8 volts output which powers distributor pickup.