Important Preliminary Checks Before Starting
Perform
Diagnostic System Check - Engine Controls
and verify that all of the following are true before
using the Symptom tables:
| • | The powertrain control module (PCM) and the malfunction indicator
lamp (MIL) are operating correctly. |
| • | The scan tool data is within a normal operating range. |
| • | Verify the customer complaint and locate the correct symptom in
the table of contents. Check the items indicated under that symptom. |
Several of the symptom procedures call for a careful visual/physical
check. DO NOT neglect to perform the visual/physical check. The visual/physical
check is an important procedure that can lead to the correction of a concern
without further diagnosis. The performance of the visual/physical check
can save valuable time. The visual/physical check should include the following:
| • | Inspect all the PCM grounds for secure and clean connections that
are in the proper location. |
| • | Check all vacuum hoses for splits, kinks, and proper connections,
as shown on the Vehicle Emission Control Information label. Check the vacuum
hoses thoroughly for any type of leak or restriction. |
| • | Inspect the air inlet ducts for collapsed or restricted sections. |
| • | Check for air leaks at throttle body mounting area and intake
manifold sealing surfaces. |
| • | Inspect the ignition system secondary wires for cracking, hardening,
carbon tracking, and the proper routing to each cylinder. |
| • | Inspect the wiring harness for proper connections and damage. |
For more symptom base diagnostics refer to the following tables:
