Automatic Trans: Diagnosis: Self-Diagnostics: Notes

PCM includes a self-diagnostic system. When a malfunction occurs, PCM will illuminate SERVICE ENGINE SOON and/or SHIFT TO D2 light located on instrument panel. When a problem is detected and light is turned on, a corresponding trouble code will be stored in PCM memory. Problems are recorded as hard failures or as intermittent failures.

PCM will also store other problems as information flags in malfunction history. Information flags will not turn on SERVICE ENGINE SOON or SHIFT TO D2 light. Information flags are used as a diagnostic tool to help technician when hard failures or intermittent failures occur.