ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-9
On-Board Diagnostic System (Vehicle with
Monitor 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 of flashing mal-
function indicator lamp (1).
• Heated oxygen sensor (if equipped)
•ECT sensor
•TP sensor
• IAT sensor
• CMP sensor
•MAF sensor
• Knock sensor
• EGR (if equipped)
•VSS
• CPU (Central Processing Unit) of ECM
ECM and malfunction indicator lamp (1) operate as follows.
• Malfunction indicator lamp (1) light when the ignition switch
is turned ON (but the engine at stop) with the diagnosis
switch terminal ungrounded regardless of the condition of
Engine and Emission control system. This is only to check
the malfunction indicator lamp (1) bulb and its circuit.
• If the above areas of Engine and Emission control system is
free from any trouble after the engine start (while engine is
running), 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.)
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 con-
nected to ground terminal (3) with a service wire 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 the trouble exists but it turns
OFF when the normal condition is restored.
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