Engine Controls - Tests W/Codes - Introduction: Summary

If the MIL does not illuminate, indicating a Diagnostic Trouble Code (DTC) has been set and there is a driveability malfunction, go to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures. Some troubleshooting steps may require resetting PCM and attempting to duplicate DTC. If malfunction is intermittent and DTC cannot be duplicated, discontinue troubleshooting procedures and go to TESTS W/O CODES article for diagnosis by symptom. If DTC cannot be duplicated, continuing with troubleshooting procedures will cause confusion and could result in unnecessary component replacement.