Test T: Malfunction Indicator Light Always On: 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) illuminates the MIL by grounding MIL control circuit.

MIL informs 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 diagnostic test. MIL will illuminate with ignition switch in RUN position and engine not running. MIL will turn OFF when the engine is started. MIL will remain illuminated if self-diagnostic system has detected a malfunction. MIL may turn OFF if malfunction no longer exists. If MIL is illuminated and engine stalls, MIL will remain illuminated as long as ignition switch is in RUN position. If MIL is not illuminated and the engine stalls, MIL will not illuminate until ignition switch is cycled OFF, then ON.