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Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> System Tests >> Mil Inoperative >> Circuit Description
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Circuit Description

There should be a steady Malfunction Indicator Light (MIL) with the ignition ON and the engine off. Ignition feed voltage is supplied directly to the MIL. The Powertrain Control Module (PCM) turns the MIL ON by grounding the MIL control circuit. No MIL with the key ON, engine not running suggests an open in the battery positive and ignition positive voltage feed fuses and circuits.

Perform the Engine Controls Diagnostic System Check, when the following conditions are present: