Important Preliminary Checks Before Starting
Perform the
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. |
| • | There are no DTCs stored. |
| • | The scan tool data is within a normal operating range. |
| • | Verify the customer concern 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 the throttle body mounting area and intake manifold
sealing surfaces. |
| • | Inspect the wiring harness for the correct connections and for damage. |
For more symptom base diagnostics refer to the following tables:
