GM Service Manual Online
For 1990-2009 cars only

Several of the symptom procedures call for a visual/physical inspection. A careful visual/physical inspection can aid in correcting a problem without further checks and can save valuable time. A visual/physical inspection should include the following items:

    •  PCM grounds for being loose, corroded, or in an improper location.
    •  Vacuum hoses for splits, kinks, and improper connections. The proper connections are shown on the Vehicle Emission Control Information label. Check the vacuum hoses for any type of leak or restriction.
    •  Air intake ducts for collapsed or damaged areas.
    •  Air leaks at throttle body mounting area, Mass Air Flow (MAF) sensor and intake manifold sealing surfaces.
    •  Ignition wires for cracking, hardness, proper routing and carbon tracking.
    •  Wiring for improper connections, pinches and cuts.