Electronic Control System: Self-diagnosis

When an abnormality occurs in the signal from a sensor, the ECM supplies ground for the malfunction indicator lamp (MIL) and stores the diagnostic trouble code (DTC) in erasable memory. When the ignition is first turned on, the ECM supplies ground to the MIL for 15 to 20 seconds to check the MIL bulb condition. If all readiness code are not set, the MIL will flash five times. If all readiness codes are set to complete, the MIL will go out. If the MIL was on but then went out, the original problem may have been an intermittent one.