On-Board Diagnostics: Notes

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

The Alternative Fuels Engine Control Module (AF ECM) is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, the AF ECM will store a Diagnostic Trouble Code (DTC) and, if code is emissions related, illuminate the Malfunction Indicator Lamp (MIL) located on instrument cluster.

There are 2 paths for accessing on-board diagnostics. It is necessary to access information through both paths, as each path presents some different information.

Generic OBD-II

This provides all generic codes and some OEM codes, serial data PIDs required for generic OBD-II and some OEM PIDs, monitor status, pending codes and freeze frame.

OEM

All DTCs, all PIDs, failure records, enhanced scan tool information and all other OEM scanner functions.