Circuit Description

The Malfunction Indicator Lamp (MIL) is used to indicate the ECM's detection of a vehicle malfunction. The instrument panel GAUGE fuse provides circuit power and the ECM provides the circuit ground that illuminates the MIL.

MIL operations should be checked visually:

The MIL should be illuminated when the ignition is first turned on. If the MIL is always ON or OFF, use the hand-held tester or OBDII scan tool and follow the procedures below to determine the cause of the problem.