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 (Service Engine Soon) are operating correctly. |
| • | Check that there are no DTC(s) stored. |
| • | Scan tool data is within 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 Careful Visual/Physical Check. 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/Physical
Check can save valuable time. The Careful Visual/Physical Check should include
the following:
| • | Inspect all 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. |
| • | Mass air flow (MAF) sensor installation is correct. |
| • | Inspect the air inlet ducts for collapsed or restricted sections. |
| • | Air leaks at throttle body mounting area, MAF sensor, 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:
