Malfunction Indicator Lamp (MIL) Always On

CIRCUIT DESCRIPTION
Battery positive voltage is supplied directly to the malfunction indicator lamp (MIL). The powertrain control module (PCM) turns the MIL ON by grounding the MIL control circuit.

MIL OPERATION
The malfunction indicator lamp (MIL) is located on the instrument panel.

MIL FUNCTION
^ The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
^ The MIL illuminates during a bulb test and a system test.
^ A diagnostic trouble code (DTC) will be stored if a MIL is requested by the diagnostic.

MIL ILLUMINATION
^ The MIL will illuminate with ignition switch ON and the engine not running.
^ The MIL will turn OFF when the engine is started.
^ The MIL will remain ON if the self-diagnostic system has detected a malfunction.
^ The MIL may turn OFF if the malfunction is not present.
^ If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON.
^ If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.

DIAGNOSTIC AIDS
If the problem is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-6:

The number below refers to the step number on the diagnostic table.
2. This step determines if the condition is with the MIL control circuit or the PCM.