Malfunction Indicator Lamp: Description and Operation

Malfunction Indicator Lamp (MIL):

PURPOSE
The Malfunction Indicator Lamp (MIL), located in the instrument cluster, illuminates to inform the driver of a malfunction. It can also be used by the technician to identify Diagnostic Trouble Codes (DTC's) stored in the Engine Control Module (ECM)

OPERATION
The MIL will illuminate while the engine is running, if a malfunction is detected in a monitored circuit or circuits, and will remain ON until the problem is repaired or is no longer detected.

Engine Control Module's Red L.E.D. (Light Emiting Diode):

The MIL will also flash simultaneously with the light emiting diode on the ECM when extracting DTC's or when inspecting feedback operation.