Test N: The Malfunction Indicator Lamp (MIL) Is Never/Always On

PINPOINT TEST N: THE MALFUNCTION INDICATOR LAMP (MIL) IS NEVER/ALWAYS ON

N1-N2:

N3-N5:

Normal Operation
The malfunction indicator lamp (MIL) is illuminated when a mis-fire condition exists or an emission-related concern is detected by the powertrain control module (PCM). The instrument cluster receives the MIL data from the PCM over the high speed controller area network (HS-CAN) communication bus. If an emissions concern exists, the PCM sets a DTC and sends a message to the instrument cluster to illuminate the MIL. If a mis-fire condition exists, the PCM sets a DTC and sends the instrument cluster a message to flash the MIL. If the MIL message is missing or if the data is deemed invalid by the instrument cluster for greater than 5 seconds, the instrument cluster sets DTC U0100 and defaults the MIL on.

NOTE: If U0100 is set in the instrument cluster other symptoms may also be present such as an inoperative speedometer, tachometer or temperature gauge.

Possible Causes
- PCM
- Instrument cluster