6-1-12 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE)
On-Board Diagnostic System (Vehicle with
Diagnosis Connector)
ECM diagnosis troubles which may occur in the area including the
following parts when the ignition switch is ON and the engine is
running, and indicates the result by turning on or flashing mal-
function indicator lamp (1).
• Heated oxygen sensor (if equipped)
• ECT sensor
• TP sensor
• IAT sensor
• MAP sensor (if equipped)
• CMP sensor
• MAF sensor
• VSS
• CPU (Central Processing Unit) of ECM
• EGR valve (if equipped)
• CKP sensor (if equipped)
• Knock sensor (if equipped)
ECM and malfunction indicator lamp (1) operate as follows.
• Malfunction indicator lamp (1) lights when the ignition switch
is turned ON (but the engine at stop) with the diagnosis
switch terminal ungrounded regardless of the condition of
Electronic Fuel Injection system. This is only to check the
malfunction indicator lamp (1) circuit.
• If the above areas of Electronic Fuel Injection system is free
from any trouble after the engine start (while engine is run-
ning), malfunction indicator lamp (1) turns OFF.
• When ECM detects a trouble which has occurred in the
above areas, it makes malfunction indicator lamp (1) turn ON
while the engine is running to warn the driver of such occur-
rence of trouble and at the same time it stores the trouble
area in ECM back-up memory. (The memory is kept as it is
even if the trouble was only temporary and disappeared
immediately. and it is not erased unless the power to ECM is
shut off for specified time below.)
ECM also indicates trouble area in memory by means of
flashing of malfunction indicator lamp (1) at the time of
inspection. (I.e. when diagnosis switch terminal (2) is
grounded and ignition switch is turned ON.)
NOTE:
When a trouble occurs in the above areas and disappears
soon while the diagnosis switch terminal is ungrounded
and the engine is running, malfunction indicator lamp (1)
lights and remains ON as long as the trouble exists but it
turns OFF when the normal condition is restored.
3. Monitor connector (white connector)
or
3
2
1
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