Engine Controls - Basic Diagnostic Procedures - 7.4L: Summary
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, no trouble codes (or only intermittent ones) were found while performing ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK and driveability problems exist, proceed to H - TESTS W/O CODES - 7.4L article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.