Malfunction Indicator Lamp Always On: Description
WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
Battery 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.