Important Preliminary Checks Before Starting
Perform the
Powertrain On Board Diagnostic (OBD) System Check
, and verify that all of the following are true
before using the Symptom Tables:
| • | The PCM and the MIL are operating correctly. |
| • | Check that there are not any DTCs that are stored. |
| • | The scan tool data is within the normal operating range. |
| • | Verify the customer complaint, and locate the correct symptom
in the table. Check the items that are indicated under that symptom. |
Several of the symptom procedures call for a careful visual inspection
and/or for a physical inspection. You MUST perform the careful visual inspection
and/or the physical inspection. The Careful Visual/Physical Check is an important
procedure that can lead to the correction a concern without further diagnosis.
The performance of the careful visual inspection and/or of the physical inspection
can save time. The careful visual inspection and/or the physical inspection
should include the following:
| • | Inspect all PCM grounds for secure connections and for clean connections
that are in the correct location. |
| • | Check for split vacuum hoses, for kinks, and for correct connections,
like shown on the label of the Vehicle Emission Control Information. Check
the vacuum hoses thoroughly for any type of leak or for a restriction. |
| • | Inspect the air inlet ducts for collapsed sections or for restricted
sections. |
| • | Check for air leaks at the mounting area for the throttle body
and at the intake manifold sealing surfaces. |
| • | Inspect the secondary wires in the ignition system for cracking,
for hardening, for carbon tracking, and for the correct routing to each cylinder. |
| • | Inspect the wiring harness for correct connections and for damage. |
Refer to the following tables for more symptom-based diagnostics.
