Test S: Malfunction Indicator Light Inoperative: Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2001 GMC Savana Special, 2001 GMC Savana Camper Special, 2001 GMC Savana, 2001 Chevrolet RV Cutaway, and 2001 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

Battery positive voltage is supplied directly to Malfunction Indicator Light (MIL). Powertrain Control Module (PCM) turns the MIL ON by grounding MIL control circuit. There should be a steady MIL with ignition switch in RUN position and the engine OFF.

MIL informs the driver that a malfunction has occurred and vehicle should be taken in for service as soon as possible. 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 will illuminate with ignition switch in RUN position and engine not running. MIL will turn OFF when engine is started. MIL will remain ON if self-diagnostic system has detected a malfunction. MIL may turn OFF if malfunction is not present. If MIL is illuminated and then engine stalls, MIL will remain illuminated so long as ignition switch is in RUN position. If MIL is not illuminated and engine stalls, MIL will not illuminate until the ignition switch is cycled OFF, then ON.