Circuit Description

The diagnostic system check - engine controls must be the starting point for any driveability complaint diagnosis. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. Perform a careful visual and physical inspection of the Powertrain Control Module (PCM) and engine grounds for being clean and tight. Diagnostic system check - engine controls is an organized approach to identifying a condition created by an electronic engine control system malfunction.

The Powertrain Control Module (PCM) controls the Malfunction Indicator Light (MIL) by providing a ground path through the MIL control circuit to turn ON the MIL. When the ignition is turned ON, the MIL will remain on until the engine is running, if no Diagnostic Trouble Codes (DTC) are stored. If MIL is illuminated, then engine stalls, the MIL will remain illuminated so long as ignition is ON.