Explorer 2WD V6-245 4.0L (1994)
Ignition Control Module: Description and Operation
EDIS Module
PURPOSE
The Electronic Distributorless Ignition System (EI), formerly (EDIS)module's primary function is to deliver full energy spark at a crank angle
targeted by the Powertrain Control Module (PCM) and to provide the PCM with crankshaft position information.
DESCRIPTION
The EI control module is a twelve pin custom microprocessor-based thick film module. Although each engine is very different in size and
structure, ICM's for each engine are very similar. With the exception of some pin assignments, basic operation of the EI systems for the different
engines is identical.
OPERATION
The EI control module (ICM) receives input from the Variable Reluctance Sensor (VRS) style Crankshaft Position (CKP) Sensor in order to
identify the passing of the missing tooth on the VRS trigger wheel.
Synchronization
The module is said to be "synchronized" when the missing tooth is found. Synchronization is essential to the ICM in order to track the angular
position of the crankshaft relative to a fixed reference and when it should fire the proper coil.
Profile Ignition Pickup
Profile Ignition Pickup (PIP) output is synthesized by the ICM using input from the VRS signal. The PIP signal generated by the ICM
indicates engine speed and crankshaft position to the PCM. The PIP signal is used by the PCM so that it can enable fuel and spark functions
and generate a Spark Angle Word (SAW) signal.
Spark Angle Word
The SAW signal provides spark targeting information to the ICM. By decoding the SAW signal and using the information it receives from the
VRS, the ICM turns the coils on and off at correct times and in proper sequence. The EI system operates at a high data rate so it can fire sparks
more accurately.
