Circuit Description
WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
There should be a steady malfunction indicator lamp (MIL) when the ignition is ON, prior to starting the engine. Battery ignition voltage is supplied to the MIL. The powertrain control module (PCM) will turn the MIL ON by grounding the control circuit at the PCM. A steady MIL with the engine running suggests a short to ground in the MIL control circuit, or a diagnostic trouble code (DTC) is stored.