Electronic Control System; Fail-Safe Function; Back-Up Function; Two Driving Cycle Detection Method - Honda Civic 2002-2003 Service Manual

Fuel and Emissions Systems
System Descriptions
Electronic Control System
The functions of the fuel and emission control systems are managed by the engine control module (ECM).
Fail-safe Function
When an abnormality occurs in the signal from a sensor, the ECM ignores that signal and assumes a pre-programmed
value
far that
sensor that allows the engine to continue to run.
Back-up Function
When an abnormality occurs in the ECM, the injectors are controlled by a back-up circuit independent of the system to
permit minimal driving.
Self-diagnosis
When an abnormality occurs in the signal from a sensor, the ECM supplies ground for the malfunction indicator lamp
(MIL) and stores the diagnostic trouble code (OTC) in erasable memory. When the ignition is first turned on, the ECM
supplies ground to the MIL for 15 to 20 seconds to check the MIL bulb condition.
Two Driving Cycle Detection Method
To prevent false indications, the "two driving cycle detection method" is used for some self-diagnostic functions.
When an abnormality occurs, the ECM stores it in its memory. When the same abnormality recurs
after the
ignition
switch is turned OFF and ON (II) again, the ECM turns on the MIl.
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