For 1990-2009 cars

### Circuit Description

The Powertrain On Board Diagnostic (OBD) System Check must be the starting point for any driveability complaint diagnosis. Perform a careful visual/physical check of the powertrain control module (PCM) and engine grounds for being clean and tight. Refer to Visual/Physical Check in Symptoms . A Powertrain On Board Diagnostic (OBD) System Check is an organized approach to identifying a problem created by an electronic engine control system malfunction.

The PCM controls the malfunction indicator lamp (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 (DTCs) are stored. If the MIL is illuminated, then the engine stalls, the MIL will remain illuminated so long as the ignition is ON. If DTC P0650 is set, this suggests a malfunction in the MIL Driver circuit.