Self-Diagnostic System: Notes

NOTE: See BASIC TESTING article for On-Board Diagnostic System Check.

NOTE: SERVICE ENGINE SOON light, located on instrument cluster, is also referred to as the Malfunction Indicator Light (MIL).

The 6.5L DEC/electronically-controlled transmission systems includes a self-diagnostic system which can determine input signal circuit malfunctions. Input signal circuits determine engine/transmission function control. When a malfunction occurs, PCM will illuminate the Malfunction Indicator Light (MIL) located on instrument cluster. When malfunction is detected and light is turned on, a corresponding Diagnostic Trouble Code (DTC) will be stored in PCM memory. To retrieve stored codes, see ENTERING & EXITING DIAGNOSTIC MODE. Malfunctions are recorded as either hard failures or intermittent failures.