System Description - Honda Accord 2008 Manual

07/11/02 09:00:01 61TA0000_110_0015

System Description

Electronic Control System
The functions of the fuel and emission control systems are managed by the engine control module (ECM) on vehicles
with manual transmissions or the powertrain control module (PCM) on vehicles with automatic transmissions.
Self-diagnosis
The ECM/PCM detects the failure of a signal from a sensor or from another control unit and stores a Temporary DTC or
a DTC. Depending on the failure, a DTC is stored in either the first or the second drive cycle. When a DTC is stored, the
ECM/PCM turns on the malfunction indicator lamp (MIL) by a signal sent to the gauge via F-CAN.
• One Drive Cycle Detection Method
When an abnormality occurs in the signal from a sensor or from another control unit, the ECM/PCM stores a DTC for
the failure and turns on the MIL immediately.
• Two Drive Cycle Detection Method
When an abnormality occurs in the signal from a sensor or from another control unit in the first drive cycle, the
ECM/PCM stores a Temporary DTC. The MIL does not come on at this time. If the failure continues in the second
drive cycle, the ECM/PCM stores a DTC and turns on the MIL.
Fail-safe Function
When an abnormality occurs in the signal from a sensor or from another control unit, the ECM/PCM ignores that signal
and substitutes a pre-programmed value for them that allows the engine to continue running. This causes a DTC to be
stored and the MIL to come on.
MIL Bulb Check and Readiness Code Condition
When the ignition switch is turned to ON (II), the ECM/PCM turns on the MIL via the F-CAN circuit for about 15 to
20 seconds to check the bulb condition. If any readiness codes are not set to complete, the MIL flashes five times. If all
readiness codes are set to complete, the MIL goes off.
Self Shut Down (SSD) Mode
After the ignition switch is turned to LOCK (0), the ECM/PCM stays on (about 40 minutes). If the ECM/PCM connector is
disconnected during this time, the ECM/PCM may be damaged. To cancel this mode, disconnect the negative cable
from the battery or jump the SCS line with the HDS after the ignition switch is turned to LOCK (0).
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