Self-Diagnostic System: Notes

NOTE: Powertrain Control Module (PCM) may also be referred to as Electronic Control Module (ECM) in some diagnostic charts and figures. Terms are used interchangeably.

Control module is equipped with a self-diagnostic system, which detects system failures or abnormalities. When a malfunction occurs, control module will store a numerical code and, in most cases, illuminate SERVICE ENGINE SOON light located on instrument panel. SERVICE ENGINE SOON light is also referred to as the Malfunction Indicator Light (MIL). Malfunctions are recorded as hard failures or as intermittent failures.

In addition to hard failures and intermittent failures, Saturn models also store information flags and codes in malfunction history. Information flags indicate a failure and will not turn on SERVICE ENGINE SOON light. Information flags and codes stored in malfunction history are used as a diagnostic tool to help technician when hard codes or intermittent problems occur and require the use of a special scan tester to retrieve diagnostic information.

NOTE: Models equipped with OBD II diagnostic systems may have additional diagnostic information and procedures available; however, to fully utilize information and procedures requires the use of a Tech 1 scan tester. See tester owners manual for additional information.