Honda 2004 Odyssey, Service Manual

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Electronic Control System
Fail-safe Function
Back-up Function
Self-diagnosis
Two Driving Cycle Detection Method
11-10
Fuel and Emissions Systems
System Descriptions
The functions of the fuel and emission control systems are managed by the powertrain control module (PCM).
When an abnormality occurs in the signal from a sensor, the PCM ignores that signal and assumes a pre-programmed
value for that sensor that allows the engine to continue to run.
(MIL) and stores the diagnostic trouble code (DTC) in erasable memory. When the ignition is first turned on, the PCM
supplies ground to the MIL for 2 seconds (’99-01 models) or for 15 to 20 seconds (’02-04 models) to check the MIL bulb
condition.
To prevent false indications, the ‘‘two driving cycle detection method’’ is used for some self-diagnostic functions.
When an abnormality occurs, the PCM stores it in its memory. When the same abnormality recurs after the ignition
switch is turned OFF and ON (II) again, the PCM turns on the MIL.
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When an abnormality occurs in the PCM, the injectors are controlled by an independent back-up circuit to permit
minimal driving.
When an abnormality occurs in the signal from a sensor, the PCM supplies ground for the malfunction indicator lamp