Malfunction Indicator Lamp: Description and Operation

MALFUNCTION INDICATOR LAMP (MIL)

ISO Standard Engine Symbol:

The MIL alerts the driver that the powertrain control module (PCM) has detected an on board diagnostics (OBD) emission-related component or system fault. When this occurs, an OBD diagnostic trouble code (DTC) is set.
- The MIL is located on the instrument cluster and is labeled as international standardization organization engine symbol.
- Power is supplied to the MIL whenever the key is in the ON or START position.
- The MIL will remain 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 will be present.
- The instrument cluster will illuminate 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):
- The bulb is damaged.
- Instrument cluster wiring concern.

- To turn off the MIL after a repair, a reset command from the diagnostic tool must be sent, or 3 consecutive drive cycles must be completed without a fault.
- For any MIL concern, GO to Quick Test QT1. QT Step 1: Powertrain Control Module (PCM)/Transaxle Control Module (TCM) Quick Test
- If the MIL blinks at a steady rate, a severe misfire condition may exist.