On-Board Diagnostic System

THE RELATIONSHIP BETWEEN DTC, MIL AND DRIVING PATTERN
1. When the same malfunction is detected and maintained during two sequential driving cycles, MIL will automatically light.
2. MIL will go off automatically after 3 sequential driving cycles without the same malfunctions.
3. 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 misfire and CKP sensor, 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 80 warm-up cycles, the diagnostic trouble code will be erased 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.




MALFUNCTION INDICATOR LAMP (MIL)
An On Board Diagnostic lamp comes on to notify the driver that there is a problem in the vehicle.
However MIL will go off automatically after 3 sequential driving cycles without the same malfunction.
Immediately after the ignition switch is turned on (ON position), the malfunction indicator light is lit continuously to indicate that the malfunction indicator light operates normally.

Following Items will be Indicated by the MIL
- Catalyst
- Fuel system
- Mass Air Flow Sensor
- Intake Air Temperature Sensor
- Engine Coolant Temperature Sensor
- Throttle Position Sensor
- Upstream Oxygen Sensor
- Downstream Oxygen Sensor Heater
- Downstream Oxygen Sensor
- Upstream Oxygen Sensor Heater
- Injector
- Misfire
- Crankshaft Position Sensor
- Camshaft Position Sensor
- Evaporative Emission Control System
- Vehicle Speed Sensor
- Idle Control Valve
- Power Supply
- ECM
- MT/AT Encording
- Acceleration Sensor
- MIL-on Request Signal
- Power Stage
- Canister Close Valve
- Fuel Tank Pressure Sensor

SELF-DIAGNOSIS
The ECM monitor the input/output signals (some signals at all times and the others under specified conditions). When the ECM detects an irregularity, it memorize the diagnostic trouble code, and outputs the signal to the self-diagnosis output terminal. The diagnosis results can be read out by the Generic Scan Tool (GST). 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 negative terminal or the engine control module (ECM) connector is disconnected or erased by the Generic Scan Tool.