Six-Step Troubleshooting Procedure

1) VERIFY PROBLEM

NOTE: For catalytic converter and feedback system to function properly, it is essential that vehicle is at operating temperature, except when attempting to diagnose cold start or cold driveability problem.

2) EXTRACT AND CLEAR FAULT CODES
- Diagnose and repair any fault code related problems before proceeding with further diagnosis.

NOTE: This process verifies that the PCM and systems are operational.

3) PERFORM VISUAL INSPECTION:
- PCM grounds for being clean, tight, and in their proper location.
- Vacuum hoses for splits, kinks and proper connections. Check thoroughly for any type of leak or restriction.
- Air leaks at throttle body mounting area and intake manifold sealing surfaces.
- Ignition wires for cracking, harness, proper routing, arcing and carbon tracking.
- Wiring for proper connections, pinches, and cuts.
- Harnesses for proper routing. Component wiring harnesses should be routed clear of ignition secondary leads.

4) PROCEED TO DIAGNOSIS BY SYMPTOM
- The following symptom charts contain groups of possible causes for each symptom and cover several engines. These procedures are not meant to be done in consecutive order. Proceed in a logical order, easiest to check or the most likely cause first. To determine if a particular system or component is used on a specific vehicle, SEE Diagrams for application.