Dodge Omni/Horizon/Rampage 1978-1989 Repair Guide

Description of System


This electronic fuel injection system is a computer regulated single point fuel injection system that provides precise air/fuel ratio for all driving conditions. At the center of this system is a digital pre-programmed computer known as a logic module that regulates ignition timing, air-fuel ratio, emission control devices and idle speed. This component has the ability to update and revise its programming to meet changing operating conditions. This system is also sometimes refered to as a Throttle Body Injection (TBI) system.

Various sensors provide the input necessary for the logic module to correctly regulate the fuel flow at the fuel injector. These include the manifold absolute pressure, throttle position, oxygen feedback, coolant temperature, charge temperature and vehicle speed sensors. In addition to the sensors, various switches also provide important information. These include the neutral-safety, heated rear window, air conditioning, air conditioning clutch switches, and an electronic idle switch.

All inputs to the logic module are converted into signals sent to the power module. These signals cause the power module to change either the fuel flow at the injector or ignition timing or both.

The logic module tests many of its own input and output circuits. If a fault is found in a major system this information is stored in the logic module. Information on this fault can be displayed tool by connecting a diagnostic readout and reading a numbered display code which directly relates to a specific fault.

Experience has shown that many complaints that may occur with EFI can be traced to poor wiring or hose connections. A visual check will help spot these most common faults and save unnecessary test and diagnosis time.