Malfunction Indicator Lamp (MIL)

MALFUNCTION INDICATOR LAMP (MIL)

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 on board diagnostic (OBD) emission-related component or system concern. When this occurs, an OBD diagnostic trouble code (DTC) sets.
- The MIL is located in the instrument cluster and is labeled CHECK ENGINE, SERVICE ENGINE SOON or the international standards organization (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 illuminates the MIL until a profile ignition pickup (PIP) signal is detected. The Ranger uses a hard wire circuit.
- The MIL remains 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 concern.
- 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.