Self-Diagnostic System: Notes
WARNING: This page is about a different car, the 1998 GMC Forward Control and 1998 Chevrolet Forward Control. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
SERVICE ENGINE SOON light, located on instrument cluster, is also referred to as the Malfunction Indicator Light (MIL).
The electronically-controlled transmission 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). When malfunction is detected and MIL is illuminated, a corresponding Diagnostic Trouble Code (DTC) will be stored in PCM memory. To retrieve stored DTC(s), see ENTERING & EXITING DIAGNOSTIC MODE . Malfunctions are recorded as either hard failures or intermittent failures.