Malfunction Indicator Lamp: Service and Repair

The Check Engine Lamp will be illuminated when the ignition switch is placed in the On position. When the engine is started, the lamp should go off. If the lamp remains on after the engine is started, the self diagnosis system has detected a problem and has stored a code in the system Electronic Control Module (ECM). After diagnosis and repair, the ECM memory can be cleared of codes by disconnecting the battery ground cable for approximately 30 seconds with ignition switch in Off position. It should be noted, when battery ground cable is disconnected to clear codes, components such as clocks, electronically tuned radios etc., will have to be reset.