Logic & Power Modules
Power to the ignition coil and fuel injector is supplied by the power module. The high current required to operate these devices requires that their power source (the power module) be isolated from the logic module to avoid electrical interference with logic module operation.
This is why the system uses 2 separate control modules. The power module is located in line with the intake air duct at the front left side of the engine compartment. The logic module, located inside the passenger compartment behind the left side kick panel, is a digital microcomputer which receives input signals from various engine switches and sensors.
The information provided by these components is used to determine ideal air/fuel ratio, spark advance, ignition coil dwell, automatic idle speed actuation and purge, and EGR control solenoid cycles.
The logic module constantly monitors its own input and output circuits for inconsistencies or other indications of component malfunction. If a fault is found in any major system, information concerning this fault, in the form of a numbered code, is stored in the logic module. See Fault Codes. The stored codes indicate specific problem areas within the system.
The power module contains those circuits necessary to power the ignition coil and fuel injector. In addition, it energizes the Automatic Shutdown (ASD) relay which activates the fuel pump, ignition coil, and the power module itself.
The module receives a signal from the distributor and sends this signal to the logic module. If this signal is absent, the ASD relay is not activated and power to the fuel pump and ignition coil is shut off. In addition, the power module contains a voltage converter which reduces battery voltage to a regulated 8.0 volt output to power the distributor and the logic module.