Engine Control Module: Description and Operation

THE engine control module (ECM) controls the following functions:

1. Multiport Fuel Injection (MFI)
The ECM receives signals from various sensors indicating changing engine operating conditions such as:
^ Intake manifold pressure (MAP)
^ Intake air temperature (IAT)
^ Engine coolant temperature (ECT)
^ Engine speed (RPM)
^ Throttle valve opening angle (TPS)
^ Exhaust oxygen content etc. (O2S)
The signals are utilized by the ECM to determine the injection duration necessary for an optimum air-fuel ratio.

2. Electronic Spark Advance (ESA)
The ECM is programmed with data for optimum ignition timing under all operating conditions.
Using data provided by sensors which monitor various engine functions (RPM, ECT, etc.). The ECM triggers the spark at precisely the right instant.

3. Diagnosis
The ECM detects any malfunctions and abnormalities in the sensor network and lights a malfunction indicator lamp (MIL) in the combination meter.At the same time, trouble is identified and a diagnostic trouble code (DTC) is recorded by the ECM. The DTC can be read by the number of blinks of the MIL when terminals TE1 and E1 of the data link connector 1 (DLC 1) are connected. The DTC are referred to in a later page.

4. Self-Correction Function
If any sensor malfunctions, an average value recorded in the back-up circuit is substituted to make driving possible. If danger is predicted, the engine is stopped and the MIL will light up.

5. Fail-Safe Function
In the event of the sensor malfunctioning, a back-up circuit will take over to provide minimal driveability, and the MIL will illuminate.