Electronic Control System
The functions of the fuel and emission control systems are managed by the engine control module (ECM).
Self-diagnosis
The ECM detects a 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 turns on the malfunction indicator lamp (MIL) by a signal sent to gauge via F-CAN.
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One Drive Cycle Detection Method
When an abnormality occurs in the signal from a sensor or from another control unit, the ECM stores a DTC for the failure and turns on the MIL immediately.
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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 stores a Temporary DTC for the failure in RAM. The MIL does not come on at this time. If the failure continues in the second drive cycle, the ECM 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 ignores that signal substitute 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
When the ignition switch is turned ON (II), the ECM supplies ground to the MIL circuit for about 15 to 20 seconds to check the bulb condition. It then goes off or blinks 5 times under various conditions. This is normal: it shows the self-testing condition of the diagnostics for the emissions control systems.