Logic & Power Modules

Power to ignition coil and fuel injector is supplied by power module. High current required to operate these devices requires that their power source (power module) be isolated from logic module to avoid electrical interference with logic module operation. Power module is located in line with intake air duct at front left side of engine compartment.

Logic module (located behind right side kick panel) is a digital micro-computer which receives input signals from various engine switches and sensors. Information provided by these components is used to determine air/fuel ratio, spark advance, ignition coil dwell, automatic idle speed actuation and purge, and EGR control solenoid cycles.

Logic module constantly monitors its own input and output circuits. If a fault is found in any major system, a numbered code is stored in the logic module. See Fault Codes. The stored codes indicate specific problem areas within the system.

Power module provides power to ignition coil and fuel injector. It also energizes Automatic Shutdown (ASD) relay, which activates fuel pump, ignition coil, and the power module itself. The module receives a signal from the distributor and sends this signal to logic module.

If this signal is absent, ASD relay is not activated and power to fuel pump and ignition coil is shut off. The power module reduces battery voltage to a regulated 8.0-volt output which powers the distributor and logic module.