Circuit Description

There should be a steady Malfunction Indicator Light (MIL) when ignition is ON, prior to starting the engine. Battery ignition voltage is supplied to MIL. The Powertrain Control Module (PCM) will turn MIL on by grounding the control circuit at PCM. A steady MIL with the engine running suggests a short to ground in MIL control circuit or a Diagnostic Trouble Code (DTC) is stored.