MIL Circuit: Description

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunction detections by the ECM. By turning the engine switch on (IG), power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.

The MIL operation can be checked visually:

When the engine switch is first turned on (IG), the MIL should be illuminated and should then turn off. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure.

If the ECM detects trouble, the MIL illuminates. At this time, the ECM records a DTC in the memory.