Self-Diagnostic System: Notes

NOTE: ECM/PCM diagnostic memory is retained by direct power supply from battery. Memory is not erased by turning off ignition, but it will be erased if battery or ECM/PCM is disconnected.

ECM/PCM has an On-Board Diagnostics-II (OBD-II) system. ECM/PCM monitors input and output signals of sensors and actuators. OBD-II also performs tests on, and monitors for deterioration of, emissions systems. When sufficient criteria are met, ECM/PCM will set a Diagnostic Trouble Code (DTC). If DTC is emission system related, Malfunction Indicator Light (MIL) will also illuminate. For non-emission related problems, DTC will set, but MIL will not illuminate. DTCs can only be read using a scan tester via OBD-II Data Link Connector (DLC). For additional information on OBD-II system, see appropriate SELF-DIAGNOSTICS article.