System Operation
SELF-DIAGNOSISThe ECM monitor the input/output signals (some signals at all times and the others under specified conditions). When the ECM detects that an irregularity, it memorizes the diagnostic trouble code, and outputs the signal to the self-diagnosis output terminal. The diagnosis results can be read out Scan Tool (ST). Diagnostic trouble code (DTC) will remain in the ECM as long as battery power is maintained. The diagnostic trouble code will, however, be erased when the battery terminal or the engine control module (ECM) connector is disconnected or erased by Generic Scan Tool.
OBD-II SYSTEM OPERATING CHART
The relationship of MIL, DTC and Driving pattern
In The Case Of MIL On
1. When the same malfunction is detected and maintained during subsequent sequential two driving cycles, MIL will automatically light up.
2. MIL will go off automatically after 3 subsequent sequential driving cycles without same malfunctions.
3. After the ECM first detects a malfunction, a diagnostic trouble code is recorded when the engine is restarted and the same malfunctions is re-detected. However, for misfire and CKP sensor a diagnostic trouble codes are recorded on the first detection of the malfunction.
4. After recording the diagnostic trouble code, if the ECM does not re-detect the malfunction for 80 warm-up cycles, the diagnostic trouble code will be released automatically from the ECM memory.
NOTE:
(1) A "warm-up cycle" means sufficient vehicle operation such that the coolant temperature has risen by at least 40 degrees Fahrenheit from engine starting and reaches a minimum temperature of 160 degrees Fahrenheit.
(2) A "driving cycle" consists of engine start-up, vehicle operation beyond the beginning of closed loop operation.