Malfunction Indicator Lamp: Description and Operation

PURPOSE/OPERATION
Among the on-board diagnostic items, a check engine/malfunction indicator lamp comes on to notify the driver of the emission control items when an irregularity is detected. However, when an irregular signal returns to normal and the engine control module judges that it has returned to normal, the check engine/malfunction indicator lamp goes out. Moreover, when the ignition switch is turned off, the lamp goes out. Even if the ignition switch is turned on again, the lamp does not come on until the irregularity is detected. Here, immediately after the ignition switch is turned on, the check engine/malfunction indicator lamp is lit for 5 seconds to indicate that the check engine/malfunction indicator lamp operates normally.

ITEMS INDICATED BY THE CHECK ENGINE/MALFUNCTION INDICATOR LAMP





Caution: The check engine/malfunction indicator lamp comes on when the line of the ignition timing adjustment terminal is shorted to ground. Therefore, the lamp also comes on when the ignition timing adjustment terminal is grounded to adjust the ignition timing, but this does not show any abnormality.

NOTE:
1. After the Engine Control Module (ECM) detects a malfunction, the check engine/malfunction indicator lamp illuminates when the engine is next turned on and the same malfunction is re-detected.
However, for items marked with a "*", the check engine/malfunction indicator lamp illuminates on the first detection of the malfunction.
2. After the check engine/malfunction indicator lamp illuminates, it will be switched off under the following conditions.
- When the ECM monitored the powertrain malfunction three times* and detected no malfunction.
*: In this case, one time indicates from engine start to stop.
- For misfiring or a fuel trim malfunction, when driving conditions (engine speed, engine coolant temperature, etc.) are similar to those when the malfunction was first recorded.