Malfunction Indicator Light Inoperative: Description
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Battery positive voltage is supplied directly to the Malfunction Indicator Light (MIL). The Powertrain Control Module (PCM) turns the MIL ON by grounding the MIL control circuit. There should be a steady Malfunction Indicator Light (MIL) with ignition on, with engine off.