Service Engine Soon

The SERVICE ENGINE SOON warning indicator Is controlled by the Powertrain Control Module (PCM) through circuit 419. The PCM turns the indicator on for approximately 3 seconds during engine start-up for a bulb check. Also, the PCM will illuminate the SERVICE ENGINE SOON warning indicator to warn the driver that an engine control malfunction has been detected which may affect engine performance. Refer to Powertrain Control Module Description in Computers and Control Systems for more information. Computers and Control Systems