Malfunction Indicator Lamp: Description and Operation

MALFUNCTION INDICATOR LAMP
As a functional test, the Malfunction Indicator Lamp (MIL) illuminates at key-on before engine cranking. Whenever the Powertrain Control Module (PCM) sets a diagnostic trouble code that effects vehicle emissions, it illuminates the MIL. The PCM illuminates the MIL only for diagnostic trouble codes that effect vehicle emissions. The MIL remains on until the diagnostic trouble code is erased. The MIL either flashes or illuminates continuously when the PCM detects active engine misfire.

During active misfire, the PCM records the current engine operating conditions.

Once the check engine lamp is lit, any one of the following conditions will turn it off.
- When the PCM has found no malfunction after monitoring the power train three times (One time is from engine start to engine stop).
- A misfire of fuel abnormality when engine speed, coolant temperature, etc. are similar to those prevailing when the malfunction was first recorded, and the PCM has detected no malfunction.







Items Indicated by the Malfunction Indicator Lamp

NOTE: Following a detected malfunction of the Powertrain Control Module, the check engine lamp lights up the next time the engine is turned on if the malfunction is still detected. However, for items marked with an asterisk (*) in the table above, the check engine lamp goes on the first time a malfunction is detected.

CAUTION: If the check engine lamp is turned on by a malfunction of the PCM, the scan tool cannot communicate with the PCM, and the diagnostic trouble code cannot be read.