Malfunction Indicator Lamp (MIL)

MALFUNCTION INDICATOR LAMP (MIL)

Malfunction Indicator Lamp (MIL) (applications With A Dedicated Hard Wire MIL Circuit):

Check Engine, Service Engine Soon, Or ISO Standard Engine Symbol:

The MIL notifies the driver that the powertrain control module (PCM) has detected an OBD emission-related component or system fault. When this occurs, an OBD diagnostic trouble code (DTC) will be set.
- The MIL is located in the instrument cluster and is labeled CHECK ENGINE, SERVICE ENGINE SOON or the ISO standard engine symbol.
- The MIL is illuminated during the instrument cluster prove out for approximately 4 seconds.
- For applications with a dedicated hard wire MIL circuit, the PCM will illuminate the MIL until a profile ignition pickup (PIP) signal is detected. For 2005, the following vehicles use a hard wire circuit: Crown Victoria/Grand Marquis, Explorer Sport Trac, and Ranger.
- The MIL will remain illuminated after instrument cluster prove out if:
- an emission related concern and DTC exists.
- no PIP signal is detected (applications with a dedicated hard-wire MIL circuit). The PIP signal is generated in the PCM using the crankshaft position (CKP) sensor. For these applications, the MIL can be helpful in diagnosing a no start.
- the PCM does not send a control message to the instrument cluster (applications with the MIL controlled through the communication link).
- the PCM is operating in the Hardware Limited Operation Strategy (HLOS).
- the MIL circuit is shorted to ground (applications with a dedicated hard wire MIL circuit).

- The MIL remains off during the instrument cluster prove out if:
- an indicator or instrument cluster concern is present.
- the MIL circuit is open (applications with a dedicated hard wire MIL circuit).

- 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 all MIL concerns, go to Symptom Charts. Symptom Related Diagnostic Procedures
- If the MIL flashes at a steady rate, a severe misfire condition may exist.
- If the MIL flashes erratically, the PCM can reset while cranking if the battery voltage is low.