Self-Diagnostic System: Notes

All vehicle are equipped with either an Electronic Control Module (ECM) or Powertrain Control Module (PCM). Unless specifically stated, references to ECM also apply to PCM equipped vehicles.

The ECM is equipped with a self-diagnostic system, which detects system failures or abnormalities. When a malfunction occurs, ECM will illuminate the SERVICE ENGINE SOON light located on instrument panel. When malfunction is detected and light is turned on, a corresponding trouble code will be stored in ECM memory. To retrieve stored codes, see READING TROUBLE CODES. Malfunctions are recorded as HARD FAILURES or as INTERMITTENT FAILURES.