MIL Circuit: Description

The MIL is used to indicate the ECM's detection of a vehicle malfunction.

The instrument panel GAUGE fuse provides the 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 switch is first turned ON. If the MIL is always ON or OFF, use the intelligent tester or OBD II scan tool and follow the procedures below to determine the cause of the problem.