Visual Inspection

Prior to retrieving DTCs, perform a comprehensive visual inspection of underhood components. Check ground connections located on intake manifold, ground cable between engine and vehicle body and battery negative cable are clean and tight. See WIRING DIAGRAMS article. Check vacuum hoses for breakage and blockage. Check electrical wiring and harness connectors for damage and/or corrosion. If problem is found, repair as necessary. After repair, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES .