Mitsubishi 3000GT Service Manual page 137

MULTIPORT FUEL INJECTION - Troubleshooting
ON-BOARD DIAGNOSTICS <From 1996 models>
The engine control module monitors the
input/output signals (some signals at all times and
the others under specified conditions) of the engine
control module.
When a malfunction has continued for a specified
time or longer since the irregular signal is initially
monitored, the engine control module judges that
a malfunction has occurred.
After the ECM first detects a malfunction, a
diagnostic trouble code is recorded when the engine
is restarted and the same malfunction is
re-detected.
However, for items marked with a I'*", a diagnostic
trouble code is recorded on the first detection of
the malfunction.
There are 50 diagnostic items, and the diagnostic
results can be read out with a scan tool.
Moreover, since memorization of the diagnostic
trouble codes is backed up directly by the battery,
the diagnostic results are memorized even if the
ignition key is turned off. The diagnostic trouble
codes will, however, be erased when the battery
terminal or the engine control module connector
is disconnected.
In addition, the diagnostic trouble code can also
be erased by turning on the ignition switch to ON
and sending the diagnostic trouble code erase
signal from the scan tool to the engine control
module.
Data
Engine coolant temperature
Engine speed
Vehicle speed
Long-term fuel compensation (Long-term fuel trim)
Short-term fuel compensation (Short-term fuel trim)
Fuel control condition
Calculation load value
Diagnostic trouble code during data recording
Caution
If the sensor connector is disconnected with
the ignition switch turned on, the diagnostic
trouble code is memorized. In this case, send
the diagnostic trouble code erase signal to the
engine control module in order to erase the
diagnostic memory.
The 50 diagnostic items are provided as follows,
and if plural items are activated, they are all
indicated sequentially from the smallest code
number.
Caution
The diagnostic trouble code of the ignition
timing adjustment signal is output whenever
terminal for ignition timing adjustment is
grounded.
Therefore, it is not a malfunction that the code
is output when adjusting ignition timing.
The ECM records the diagnostic trouble code and
the engine operating conditions at the time the
malfunction was detected. These data are called
"freeze frame" data.
This data indicates the engine operating condition
from when nothing at all is detected to the initial
detection of malfunction.
This data can be read by using the scan tool, and
can then be used in simulation tests for
troubleshooting. Data items are as follows.
TSB Revision
Unit
km/h
Closed loop
l
Open loop - drive condition
l
Open loop - DTC set
l
Closed loop - 02 (rear) failed
l