Preliminary Checks

Before using this article you should have already performed the On-Board Diagnostic (OBD II) System Check 

Perform a thorough visual inspection. This inspection can often lead to correcting a problem without further checks and can save valuable time. Inspect for the following conditions:

• Engine Control Module (ECM) grounds for being clean, tight, and in their proper location
• Vacuum hoses for splits, kinks, collapsing and proper connections as shown on the Vehicle Emission Control Information label. Inspect thoroughly for any type of leak or restriction.
• Air leaks at the throttle body mounting area and the intake manifold sealing surfaces
• Ignition wires for cracks, hardness, proper routing, and carbon tracking
• Wiring for proper connections
• Wiring for pinches or cuts