Description and Operation

Description

If gasoline engine control system components (sensors, ECM, injector(s), etc.) malfunction, fuel supply may be interrupted or the proper amount of fuel required for various engine service functions may not be supplied. You may notice one of the following conditions.

1. 1
   Engine does not start or is difficult to start.
2. 2
   Idle speed is unstable.
3. 3
   Poor engine performance

If you encounter any of the above conditions, first perform basic diagnostics, including basic engine checks (ignition system malfunction, incorrect engine adjustment, etc.). Then inspect the gasoline engine control system components using the scan tool (GRS).MIL (CHECK ENGINE LIGHT) [OBD]: The MIL illuminates to warn the driver of a malfunction in the emission control system. The MIL automatically turns off after 3 consecutive driving cycles without the same malfunction. Immediately after the ignition switch is turned ON (engine not running), the MIL illuminates continuously to show that it is operating correctly. The MIL illuminates to indicate the following malfunctions:

• CATALYTIC CONVERTER
• Fuel system
• MASS AIR FLOW SENSOR
• INTAKE AIR TEMPERATURE SENSOR
• Engine Coolant Temperature Sensor
• THROTTLE POSITION SENSOR
• Heated oxygen sensor (upstream)
• Heated oxygen sensor heater (upstream)
• Heated oxygen sensor (downstream)
• Heated oxygen sensor heater (downstream)
• INJECTOR
• misfire
• CRANKSHAFT POSITION SENSOR (CKP)
• CAMSHAFT POSITION SENSOR
• Evaporative Emission Control System
• Vehicle speed sensor
• Idle Speed Control System
• POWER SOURCE
• PCM/PCM
• MT/AT Coding
• WITH ACCELERATION SENSOR
• MIL request signal
• Power level

[NON-OBD]: The MIL illuminates to warn the driver of a malfunction in the emission control system. The MIL automatically turns off after 3 consecutive driving cycles without the same malfunction. Immediately after the ignition switch is turned ON (engine not running), the MIL illuminates continuously to show that it is operating correctly. The MIL illuminates to indicate malfunctions of the following items:

• HEATED OXYGEN SENSOR (HO2S)
• MASS AIR FLOW SENSOR (MAFS)
• THROTTLE POSITION SENSOR (TPS)
• ENGINE COOLANT TEMPERATURE SENSOR (ECTS)
• IDLE SPEED CONTROL (ISC) Actuator
• INJECTORS
• ECM

[MONITOR]

1. 1
   After turning the ignition switch ON, make sure the warning lamp illuminates for about 5 seconds, then turns off.
2. 2
   If the lamp does not illuminate, check the circuit for an open circuit, a blown fuse, or a burned-out bulb.

The ECM self-diagnosis monitors input/output signals (some signals continuously, others only under specific conditions). When the ECM detects a malfunction, it stores the diagnostic trouble code (DTC) for the symptom and transmits a signal over the data communication line. The diagnosis can be read using the MIL or GDS. As long as battery voltage is maintained, DTCs are stored in the ECM memory. However, DTCs are erased once the battery terminal or ECM connector is disconnected or when the GDS is used to clear them.RELATIONSHIP BETWEEN TROUBLE CODE AND DRIVING MODE IN EOBD SYSTEM

1. 1
   When the same malfunction is detected during two consecutive driving cycles, the MIL automatically illuminates.
2. 2
   The MIL automatically turns off if the malfunction does not recur for three consecutive driving cycles.
3. 3
   If an abnormality occurs in two consecutive driving cycles, the DTC is stored in ECM memory. The MIL illuminates when the malfunction occurs during the second driving cycle. When a misfire is detected, the DTC is stored and the MIL illuminates immediately after the malfunction is detected.
4. 4
   The diagnostic trouble code (DTC) is automatically erased from ECM memory if the same malfunction is not detected during 40 driving cycles.