Malfunction Indicator Lamp

If the Malfunction Indicator Lamp (MIL) remains lit, the self-diagnostic system has detected a malfunction. If the malfunction goes away, the MIL will go out immediately but a corresponding Diagnostic Trouble Code (DTC) will be stored in the memory of the Engine Control Module (ECM). DTC 41 (Ignition Signal Circuit), however, is an exception to this statement and is not stored in ECM memory. Any memory of DTC 41 is erased as soon as the ignition switch is turned to the "LOCK" position. In order to detect an active DTC 41, the engine must be cranked for 3 seconds and the Tech 1 scan tool diagnostic computer connected with the ignition switch left in "ON." If the ignition switch is turned to "LOCK" at any time during this procedure, a present DTC 41 will be lost. For further DTC retrieval information, refer to Accessing and Reading Diagnostic Trouble Codes. Testing and Inspection