Malfunction Indicator Lamp: Description and Operation

MALFUNCTION INDICATOR LAMP (MIL)

The MIL alerts the driver that the powertrain control module (PCM) has detected an on board diagnostic (OBD) emission-related component or system concern. When this occurs, an OBD diagnostic trouble code (DTC) is set.
- The MIL is located on the instrument cluster and is labeled as International Standards Organization (ISO) engine symbol.
- Power is supplied to the MIL whenever the ignition is in the ON or START position.
- The MIL remains on in the on/start mode as a bulb check during the instrument cluster prove-out for approximately 4 seconds.
- If the MIL remains on after the bulb check:
- the PCM illuminates the MIL for an emission related concern and a DTC is set.
- the instrument cluster illuminates the MIL if the PCM does not send a control message to the instrument cluster.
- the PCM is operating in the hardware limited operation strategy (HLOS).

- If the MIL remains off during the bulb check, there is:
- an instrument cluster concern.
- an instrument cluster wiring concern.

- To turn off the MIL after a repair, a reset command from the scan tool must be sent, or three consecutive drive cycles must be completed without a concern.
- For any MIL concern, refer to Symptom Charts, GO to Quick Test QT1. QT: Powertrain Control Module (PCM)/Transaxle Control Module (TCM) Quick Test
- If the MIL blinks at a steady rate, a severe misfire condition may exist.
- The MIL flashes after a period of time with the ignition in the RUN position (engine not running) if DTC P1000 is set.





ISO Standard Engine Symbol