Visual Inspection

Prior to retrieving DTCs, perform a comprehensive visual inspection of ground connections located on intake manifold, ensure battery negative cable is okay, and check ground cable between engine and vehicle body. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Check vacuum hoses for breakage and blockage. Check electrical wiring and connectors for damage and corrosion. If problem is found, repair as necessary. After repair, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES .